Plants are
livingLife is a characteristic that distinguishes objects that have self-sustaining biological processes from those that do not—either because such functions have ceased , or else because they lack such functions and are classified as "inanimate."In biology, the science of living organisms, "life"...
organismIn biology, an organism is any living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homeostasis as a stable whole...
s belonging to the
kingdomIn biological taxonomy, kingdom and/or regnum is a taxonomic rank in either the highest rank, or the rank below domain. Each kingdom is divided into smaller groups called phyla...
Plantae. They include familiar organisms such as
treeA tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s,
herbA herb is a plant that is valued for flavor, scent, or other qualities. Herbs are used in cooking, as medicines, and for spiritual purposes....
s, bushes,
grassGrasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns...
es,
vineThe term vine may refer to a climbing or trailing plant. The word, derived from Latin vīnea, in the original sense referred to the grapevines . The modern extended sense is mostly restricted to North American English, which uses "grapevine" to refer to the grape-bearing Vitis species...
s,
fernA fern is any one of a group of about 20,000 species of plants classified in the phylum or division Pteridophyta, also known as Filicophyta. The group is also referred to as Polypodiophyta, or Polypodiopsida when treated as a subdivision of tracheophyta...
s,
mossMosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...
es, and
green algaeThe green algae are the large group of algae from which the embryophytes emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic...
. The scientific study of plants, known as
botanyBotany, plant science, phytology, or plant biology is a branch of biology and is the scientific study of plant life and development...
, has identified about 350,000 extant
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
of plants, defined as seed plants,
bryophyteBryophytes are all embryophytes that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. They neither have flowers nor produce seeds, reproducing via spores...
s,
fernA fern is any one of a group of about 20,000 species of plants classified in the phylum or division Pteridophyta, also known as Filicophyta. The group is also referred to as Polypodiophyta, or Polypodiopsida when treated as a subdivision of tracheophyta...
s and fern allies. As of 2004, some 287,655 species had been identified, of which 258,650 are flowering and 18,000
bryophyteBryophytes are all embryophytes that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. They neither have flowers nor produce seeds, reproducing via spores...
s (see table below).
Green plants, sometimes called
Viridiplantae, obtain most of their energy from
sunlightElectromagnetic radiation is a ubiquitous phenomenon that takes the form of self-propagating waves in a vacuum or in matter. It consists of electric and magnetic field components which oscillate in phase perpendicular to each other and perpendicular to the direction of energy propagation...
via a process called
photosynthesisPhotosynthesis is a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of Bacteria, but not in Archaea...
.
Definition
AristotleAristotle was a Greek philosopher, a student of Plato and teacher of Alexander the Great. He wrote on many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, politics, government, ethics, biology, and zoology.Together with Plato and Socrates , Aristotle is one of...
divided all living things between plants (which generally do not move), and animals (which often are mobile to catch their food). In
LinnaeusCarl Linnaeus was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature...
' system, these became the
KingdomsIn biological taxonomy, kingdom and/or regnum is a taxonomic rank in either the highest rank, or the rank below domain. Each kingdom is divided into smaller groups called phyla...
Vegetabilia (later Metaphyta or Plantae) and Animalia (also called Metazoa). Since then, it has become clear that the Plantae as originally defined included several unrelated groups, and the
fungiA fungus is any member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. The Fungi are classified as a kingdom that is separate from plants, animals and bacteria...
and several groups of
algaeAlgae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds. They are photosynthetic, like plants, and "simple" because they lack the many distinct organs found in...
were removed to new kingdoms. However, these are still often considered plants in many contexts, both technical and popular.
Current definitions of Plantae
When the name Plantae or plants is applied to a specific taxon, it is usually referring to one of three concepts. From smallest to largest in inclusiveness, these three groupings are:
| Name(s) |
Scope |
Description |
Land plantThe embryophytes are the most familiar group of plants. They are often called land plants because they live primarily in terrestrial habitats, in contrast with the related green algae that are primarily aquatic. The embryophytes include trees, flowers, ferns, mosses, and various other green land...
s, also known as Embryophyta or Metaphyta. |
Plantae sensu strictissimo Sensu is a Latin term meaning "in the sense of".It is used in fields including biology, geology and law in the phrases sensu stricto or stricto sensu , and sensu lato or lato sensu ....
|
As the narrowest of plant categories, this is further delineated below. |
| Green plants - also known as Viridiplantae Viridiplantae are a clade comprising the green algae and land plants.In some classification systems they have been treated as a kingdom, under various names, e.g...
, Viridiphyta or Chlorobionta |
Plantae sensu stricto Sensu is a Latin term meaning "in the sense of".It is used in fields including biology, geology and law in the phrases sensu stricto or stricto sensu , and sensu lato or lato sensu ....
|
Comprise the above Embryophytes, CharophytaThe Charophyta are a division of green algae, including the closest relatives of the embryophyte plants. In some groups, such as conjugating green algae, flagellate cells do not occur. The latter group does engage in sexual reproduction, and motility does not involve flagella, since they are...
(i.e., primitive stoneworts), and ChlorophytaChlorophyta, a division of green algae, includes about 7,000 species of mostly aquatic photosynthetic eukaryotic organisms. Like the land plants , green algae contain chlorophylls a and b, and store food as starch in their plastids...
(i.e., green algaeThe green algae are the large group of algae from which the embryophytes emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic...
such as sea lettuceThe sea lettuces comprise the genus Ulva, a group of edible green algae widely distributed along the coasts of the world's oceans....
). Viridiplantae encompasses a group of organisms that possess chlorophyllChlorophyll is a green pigment found in most plants, algae, and cyanobacteria. Its name is derived from the Greek χλωρός and φύλλον...
a and b, have plastidPlastids are major organelles found in the cells of plants and algae. Plastids are the site of manufacture and storage of important chemical compounds used by the cell...
s that are bound by only two membranes, are capable of storing starch, and have celluloseCellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
in their cell wallA cell wall is a tough, flexible and sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to act as a...
s. It is this cladeA clade is a term used in modern alpha taxonomy, the scientific classification of living and fossil organisms, to describe a monophyletic group, defined as a group consisting of a single common ancestor and all its descendants.[The term "monophyletic group" is used in this article...]
which is mainly the subject of this article. |
ArchaeplastidaThe Archaeplastida are a major line of eukaryotes, comprising the land plants, green and red algae, and a small group called the glaucophytes. All of these organisms have plastids surrounded by two membranes, suggesting they developed directly from endosymbiotic cyanobacteria...
, Plastida or Primoplantae |
Plantae sensu lato Sensu is a Latin term meaning "in the sense of".It is used in fields including biology, geology and law in the phrases sensu stricto or stricto sensu , and sensu lato or lato sensu ....
|
Comprises the green plants above, as well as Rhodophyta (red algae) and Glaucophyta (simple glaucophyte algae). As the broadest plant clade, this comprises most of the eukaryote A eukaryote is an organism whose cells contain complex structures enclosed within membranes. The defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear envelope, within which the genetic material is carried...
s that eons ago acquired their chloroplastChloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.The word chloroplast is...
s directly by engulfing cyanobacteriaCyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of bacteria that obtain their energy through photosynthesis. The name "cyanobacteria" comes from the color of the bacteria = blue)...
. |
Outside of formal scientific contexts, the term "plant" implies an association with certain traits, such as multicellularity, cellulose, and photosynthesis. Many of the classification controversies involve organisms that are rarely encountered and are of minimal apparent economic significance, but are crucial in developing an understanding of the evolution of modern flora.
Algae
Most
algaeAlgae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds. They are photosynthetic, like plants, and "simple" because they lack the many distinct organs found in...
are no longer classified within the Kingdom Plantae. The algae comprise several different groups of organisms that produce energy through photosynthesis, each of which arose independently from separate non-photosynthetic ancestors. Most conspicuous among the algae are the
seaweedSeaweedSeaweed has antioxidents. Is a loose colloquial term encompassing macroscopic, multicellular, benthic marine algae. The term includes some members of the red, brown and green algae...
s, multicellular algae that may roughly resemble terrestrial plants, but are classified among the
greenThe green algae are the large group of algae from which the embryophytes emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic...
,
redThe red algae are one of the oldest groups of eukaryotic algae, and also one of the largest, with about 5,000–6,000 species of mostly multicellular, marine algae, including many notable seaweeds...
, and
brown algaeThe Phaeophyceae or brown algae, is a large group of mostly marine multicellular algae, including many seaweeds of colder Northern Hemisphere waters. They play an important role in marine environments both as food, and for the habitats they form...
. Each of these algal groups also includes various microscopic and single-celled organisms.
The two groups of green algae are the closest relatives of land plants (
embryophyteThe embryophytes are the most familiar group of plants. They are often called land plants because they live primarily in terrestrial habitats, in contrast with the related green algae that are primarily aquatic. The embryophytes include trees, flowers, ferns, mosses, and various other green land...
s). The first of these groups is the
CharophytaThe Charophyta are a division of green algae, including the closest relatives of the embryophyte plants. In some groups, such as conjugating green algae, flagellate cells do not occur. The latter group does engage in sexual reproduction, and motility does not involve flagella, since they are...
(
desmidDesmids are an order of green algae, comprising around 40 genera and 5,000 to 6,000 species, found mostly but not exclusively in fresh water. Most are unicellular, and are divided into two compartments separated by a narrow bridge or isthmus...
s and stoneworts), from which the embryophytes developed. The sister group to the combined embryophytes and charophytes is the other group of green algae,
ChlorophytaChlorophyta, a division of green algae, includes about 7,000 species of mostly aquatic photosynthetic eukaryotic organisms. Like the land plants , green algae contain chlorophylls a and b, and store food as starch in their plastids...
, and this more inclusive group is collectively referred to as the green plants or Viridiplantae. The Kingdom Plantae is often taken to mean this monophyletic grouping. With a few exceptions among the green algae, all such forms have cell walls containing
celluloseCellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
, have
chloroplastChloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.The word chloroplast is...
s containing
chlorophyllChlorophyll is a green pigment found in most plants, algae, and cyanobacteria. Its name is derived from the Greek χλωρός and φύλλον...
s
a and
b, and store food in the form of
starchStarch or amylum is a polysaccharide carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds.Starch is produced by all green plants as an energy store and is a major food source for humans....
. They undergo closed
mitosisMitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets in two daughter nuclei. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two daughter cells containing...
without
centrioleA centriole is a barrel-shaped cell structure found in most animal eukaryotic cells, though absent in higher plants and most fungi. The walls of each centriole are usually composed of nine triplets of microtubules...
s, and typically have
mitochondriaIn cell biology, a mitochondrion is a membrane-enclosed organelle found in most eukaryotic cells. These organelles range from 0.5–10 micrometers in diameter...
with flat cristae.
The
chloroplastChloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.The word chloroplast is...
s of green plants are surrounded by two membranes, suggesting they originated directly from endosymbiotic
cyanobacteriaCyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of bacteria that obtain their energy through photosynthesis. The name "cyanobacteria" comes from the color of the bacteria = blue)...
. The same is true of two additional groups of algae: the Rhodophyta (red algae) and Glaucophyta. All three groups together are generally believed to have a common origin, and so are classified together in the taxon
ArchaeplastidaThe Archaeplastida are a major line of eukaryotes, comprising the land plants, green and red algae, and a small group called the glaucophytes. All of these organisms have plastids surrounded by two membranes, suggesting they developed directly from endosymbiotic cyanobacteria...
. In contrast, most other algae (e.g.
heterokontThe heterokonts or stramenopiles are a major line of eukaryotes presently containing more than 100,000 known species, most of them diatoms. Most are algae, ranging from the giant multicellular kelp to the unicellular diatoms, which are a primary component of plankton...
s,
haptophyteThe haptophytes, classed either as the Prymnesiophyta or Haptophyta, are a phylum of algae.The term "Haptophyceae" is sometimes used. This ending implies classification at a lower level...
s,
dinoflagellateThe dinoflagellates are a large group of flagellate protists. Most are marine plankton, but they are common in fresh water habitats as well. Their populations are distributed depending on temperature, salinity, or depth. About half of all dinoflagellates are photosynthetic, and these make up the...
s, and
euglenidThe euglenids are one of the best-known groups of flagellates, commonly found in freshwater especially when it is rich in organic materials, with a few marine and endosymbiotic members. Many euglenids have chloroplasts and produce energy through photosynthesis, but others feed by phagocytosis or...
s) have chloroplasts with three or four surrounding membranes. They are not close relatives of the green plants, presumably acquiring chloroplasts separately from ingested or symbiotic green and red algae.
Fungi
FungiA fungus is any member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. The Fungi are classified as a kingdom that is separate from plants, animals and bacteria...
were previously included in the plant kingdom, but are now seen to be more closely related to animals. Unlike embryophytes and algae which are generally photosynthetic, fungi are often saprotrophs: obtaining food by breaking down and absorbing surrounding materials. Most fungi are formed by microscopic structures called
hyphaA hypha is a long, branching filamentous cell of a fungus, and also of unrelated Actinobacteria. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium; yeasts are unicellular fungi that do not grow as hyphae.-Structure:A hypha consists of one or more...
e, which may or may not be divided into cells but contain eukaryotic
nucleiIn cell biology, the nucleus , also sometimes referred to as the "control center", is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as...
. Fruiting bodies, of which
mushroomA mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. The standard for the name "mushroom" is the cultivated white button mushroom, Agaricus bisporus, hence the word mushroom is most often applied to those fungi that have...
s are most familiar, are the reproductive structures of fungi. They are not related to any of the photosynthetic groups, but are close relatives of
animalAnimals are a major group of mostly multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously...
s. Therefore, the fungi are in a kingdom of their own.
Diversity
About 350,000
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
of plants, defined as seed plants,
bryophyteBryophytes are all embryophytes that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. They neither have flowers nor produce seeds, reproducing via spores...
s,
fernA fern is any one of a group of about 20,000 species of plants classified in the phylum or division Pteridophyta, also known as Filicophyta. The group is also referred to as Polypodiophyta, or Polypodiopsida when treated as a subdivision of tracheophyta...
s and fern allies, are estimated to exist currently. As of 2004, some 287,655 species had been identified, of which 258,650 are
flowering plantThe flowering plants or angiosperms are the most diverse group of land plants. The flowering plants and the gymnosperms are the only extant groups of seed plants...
s, 16,000
bryophyteBryophytes are all embryophytes that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. They neither have flowers nor produce seeds, reproducing via spores...
s, 11,000
fernA fern is any one of a group of about 20,000 species of plants classified in the phylum or division Pteridophyta, also known as Filicophyta. The group is also referred to as Polypodiophyta, or Polypodiopsida when treated as a subdivision of tracheophyta...
s and 8,000
green algaeThe green algae are the large group of algae from which the embryophytes emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic...
.
Diversity of living plant divisions
| Informal group |
Division name |
Common name |
No. of living species |
| Green algae The green algae are the large group of algae from which the embryophytes emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic...
|
ChlorophytaChlorophyta, a division of green algae, includes about 7,000 species of mostly aquatic photosynthetic eukaryotic organisms. Like the land plants , green algae contain chlorophylls a and b, and store food as starch in their plastids...
|
green algae The green algae are the large group of algae from which the embryophytes emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic...
(chlorophytes) |
3,800 |
CharophytaThe Charophyta are a division of green algae, including the closest relatives of the embryophyte plants. In some groups, such as conjugating green algae, flagellate cells do not occur. The latter group does engage in sexual reproduction, and motility does not involve flagella, since they are...
|
green algae The green algae are the large group of algae from which the embryophytes emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic...
(desmidDesmids are an order of green algae, comprising around 40 genera and 5,000 to 6,000 species, found mostly but not exclusively in fresh water. Most are unicellular, and are divided into two compartments separated by a narrow bridge or isthmus...
s & charophytes) |
4,000 - 6,000 |
BryophyteBryophytes are all embryophytes that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. They neither have flowers nor produce seeds, reproducing via spores...
s |
MarchantiophytaThe Marchantiophyta are a division of bryophyte plants commonly referred to as hepatics or liverworts. Like other bryopeos, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information....
|
liverworts |
6,000 - 8,000 |
| Anthocerotophyta |
hornworts |
100 - 200 |
BryophytaMosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...
|
mosses |
12,000 |
| Pteridophyte The pteridophytes are vascular plants that neither flower nor produce seeds, hence they are called vascular cryptogams...
s |
Lycopodiophyta The Division Lycopodiophyta is a tracheophyte subdivision of the Kingdom Plantae. It is the oldest extant vascular plant division at around 420 million years old, and includes some of the most "primitive" extant species...
|
club mosses |
1,200 |
| Pteridophyta |
ferns, whisk ferns & horsetails |
11,000 |
| Seed plants |
CycadCycads are a group of seed plants characterized by a large crown of compound leaves and a stout trunk. They are evergreen, gymnospermous, dioecious plants having large pinnately compound leaves...
ophyta |
cycads |
160 |
| Ginkgophyta |
ginkgo |
1 |
PinophytaThe conifers, division Pinophyta, also known as division Coniferophyta or Coniferae, are one of 13 or 14 division level taxa within the Kingdom Plantae. Pinophytes are gymnosperms. They are cone-bearing seed plants with vascular tissue; all extant conifers are woody plants, the great majority...
|
conifers |
630 |
GnetophytaThe plant division Gnetophyta or gnetophytes comprise three related families of woody plants grouped in the gymnosperms. The gnetophytes differ from other gymnosperms in having vessel elements as in the flowering plants....
|
gnetophytes |
70 |
| Magnoliophyta The flowering plants or angiosperms are the most diverse group of land plants. The flowering plants and the gymnosperms are the only extant groups of seed plants...
|
flowering plants |
258,650 |
The naming of plants is governed by the
International Code of Botanical NomenclatureThe International Code of Botanical Nomenclature is the set of rules and recommendations dealing with the formal botanical names that are given to plants. Its intent is that each taxonomic group of plants has only one correct name that is accepted worldwide...
and
International Code of Nomenclature for Cultivated PlantsThe International Code of Nomenclature for Cultivated Plants regulates the naming of cultivars, cultivar Groups and graft-chimaeras...
(see
cultivated plant taxonomyCultivated plant taxonomy is the study of the theory and practice of the science that finds, describes, classifies, identifies, and names cultigens – those plants whose origin or selection is primarily due to intentional human activity....
).
Phylogeny
A proposed phylogeny of the Plantae after Kenrick and Crane is as follows, with modification to the Pteridophyta from Smith et al. The
PrasinophyceaeIn taxonomy, Prasinophytes are a class of the Division Chlorophyta. These are primitive eukaryotic, marine green algae. Its best known genus is Ostreococcus , which is considered to be the smallest free-living eukaryote and which has been detected in marine samples around the world...
may be a paraphyletic basal group to all green plants.
Embryophytes
The plants that are likely most familiar to us are the multicellular land plants, called
embryophyteThe embryophytes are the most familiar group of plants. They are often called land plants because they live primarily in terrestrial habitats, in contrast with the related green algae that are primarily aquatic. The embryophytes include trees, flowers, ferns, mosses, and various other green land...
s. They include the
vascular plantVascular plants are those plants that have lignified tissues for conducting water, minerals, and photosynthetic products through the plant. Vascular plants include the ferns, clubmosses, flowering plants, conifers and other gymnosperms...
s, plants with full systems of
leavesIn botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin. There is continued debate about whether the flatness of leaves evolved to expose the chloroplasts to more light or to increase the absorption of carbon dioxide. In...
,
stemsA stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , cones or other stems etc. The internodes act as spaces that distance one node from another...
, and
rootIn vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...
s. They also include a few of their close relatives, often called
bryophyteBryophytes are all embryophytes that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. They neither have flowers nor produce seeds, reproducing via spores...
s, of which
mossMosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...
es and
liverwortsThe Marchantiophyta are a division of bryophyte plants commonly referred to as hepatics or liverworts. Like other bryopeos, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information....
are the most common.
All of these plants have
eukaryoticA eukaryote is an organism whose cells contain complex structures enclosed within membranes. The defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear envelope, within which the genetic material is carried...
cells with
cell wallA cell wall is a tough, flexible and sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to act as a...
s composed of
celluloseCellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
, and most obtain their energy through
photosynthesisPhotosynthesis is a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of Bacteria, but not in Archaea...
, using
lightLight is electromagnetic radiation, particularly radiation of a wavelength that is visible to the human eye ....
and
carbon dioxideCarbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state...
to synthesize food. About three hundred plant species do not photosynthesize but are parasites on other species of photosynthetic plants. Plants are distinguished from green algae, which represent a mode of photosynthetic life similar to the kind modern plants are believed to have evolved from, by having specialized reproductive organs protected by non-reproductive tissues.
Bryophytes first appeared during the early
PaleozoicThe Paleozoic or Palaeozoic Era is the earliest of three geologic eras of the Phanerozoic eon...
. They can only survive where moisture is available for significant periods, although some species are desiccation tolerant. Most species of bryophyte remain small throughout their life-cycle. This involves an alternation between two generations: a haploid stage, called the
gametophyteIn plants and algae that undergo alternation of generations, a gametophyte is the multicellular structure, or phase, that is haploid, containing a single set of chromosomes:...
, and a diploid stage, called the
sporophyteAll land plants, and some algae, have life cycles in which a haploid gametophyte generation alternates with a diploid sporophyte, the generation of a plant or alga that has a double set of chromosomes. A multicellular sporophyte generation or phase is present in the life cycle of all land plants...
. The sporophyte is short-lived and remains dependent on its parent gametophyte.
Vascular plants first appeared during the
SilurianThe Silurian is a geologic period and system that extends from the end of the Ordovician period, about 443.7 ± 1.5 Ma , to the beginning of the Devonian period, about 416.0 ± 2.8 Ma . As with other geologic periods, the rock beds that define the period's start and end are well identified, but the...
period, and by the
DevonianThe Devonian is a geologic period and system of the Paleozoic era spanning from . It is named after Devon, England, where rocks from this period were first studied....
had diversified and spread into many different land environments. They have a number of adaptations that allowed them to overcome the limitations of the bryophytes. These include a cuticle resistant to desiccation, and vascular tissues which transport water throughout the organism. In most the sporophyte acts as a separate individual, while the gametophyte remains small.
The first primitive seed plants, Pteridosperms (seed ferns) and Cordaites, both groups now extinct, appeared in the late Devonian and diversified through the Carboniferous, with further evolution through the
PermianThe Permian
[The term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named...]
and
TriassicThe Triassic is a geologic period and system that extends from about 251 to 199 Ma . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
periods. In these the gametophyte stage is completely reduced, and the sporophyte begins life inside an enclosure called a
seedA seed , referred to as a kernel in some plants, is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
, which develops while on the parent plant, and with fertilisation by means of
pollenPollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement between the stamens to the pistil of flowering plants or from the male cone to the...
grains. Whereas other vascular plants, such as ferns, reproduce by means of spores and so need moisture to develop, some seed plants can survive and reproduce in extremely arid conditions.
Early seed plants are referred to as
gymnospermGymnosperm is a group of spermatophyte seed-bearing plants with ovules on scales, which are usually arranged in cone-like structures....
s (naked seeds), as the seed embryo is not enclosed in a protective structure at pollination, with the pollen landing directly on the embryo. Four surviving groups remain widespread now, particularly the conifers, which are dominant
treeA tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s in several
biomeBiome are climatically and geographically defined areas of ecologically similar climatic conditions such as communities of plants, animals, and soil organisms, and are often referred to as ecosystems...
s. The angiosperms, comprising the flowering plants, were the last major group of plants to appear, emerging from within the gymnosperms during the
JurassicThe Jurassic is a geologic period and system that extends from about Ma to Ma, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the "Age of Reptiles". The start of the period is marked by...
and diversifying rapidly during the
CretaceousThe Cretaceous , Latin language for "chalky", usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago . In the geologic timescale, the Cretaceous follows on the Jurassic period and is followed by the Paleogene period of the...
. These differ in that the seed embryo (angiosperm) is enclosed, so the pollen has to grow a tube to penetrate the protective seed coat; they are the predominant group of flora in most biomes today.
Fossils
Plant
fossilFossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous rock formations and sedimentary layers is known as the fossil record...
s include roots, wood, leaves, seeds, fruit,
pollenPollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement between the stamens to the pistil of flowering plants or from the male cone to the...
,
sporeIn biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions...
s,
phytolithA phytolith is a rigid microscopic body that occurs in many plants. The most common type of phytolith is the silica phytolith, also called opal phytolith. Silica phytoliths vary in size and shape depending on the plant taxon and plant part in which they occur...
s, and
amberAmber is fossilized tree resin , which has been appreciated for its color and natural beauty since neolithic times. Good quality amber is used for the manufacture of ornamental objects and jewelry...
(the fossilized resin produced by some plants). Fossil land plants are recorded in terrestrial, lacustrine, fluvial and nearshore marine sediments.
PollenPollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement between the stamens to the pistil of flowering plants or from the male cone to the...
, spores and algae (
dinoflagellateThe dinoflagellates are a large group of flagellate protists. Most are marine plankton, but they are common in fresh water habitats as well. Their populations are distributed depending on temperature, salinity, or depth. About half of all dinoflagellates are photosynthetic, and these make up the...
s and
acritarchAcritarchs are small organic fossils, present from approximately to the present. Their diversity reflects major ecological events such as the appearance of predation and the Cambrian explosion.-Definition:In general, any small, non-acid soluble Acritarchs are small organic fossils, present from...
s) are used for dating sedimentary rock sequences. The remains of fossil plants are not as common as fossil animals, although plant fossils are locally abundant in many regions worldwide.
The earliest fossils clearly assignable to Kingdom Plantae are fossil green algae from the
CambrianThe Cambrian is the first geological period of the Paleozoic era, lasting from ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux...
. These fossils resemble
calcifiedCalcification is the process in which calcium salts build up in soft tissue, causing it to harden. Calcifications may be classified on whether there is mineral balance or not, and the location of the calcification.-Mineral balance:...
multicellular members of the
DasycladalesIn taxonomy, the Dasycladales is an order of large unicellular green algae in the class Ulvophyceae. It contains two families, the Dasycladaceae and the Polyphysaceae....
. Earlier
PrecambrianThe Precambrian is an informal name for the span of time before the current Phanerozoic Eon, and is divided into several eons of the geologic timescale. It spans from the formation of Earth around 4500 Ma to the beginning of the Cambrian Period, when macroscopic hard-shelled animals first...
fossils are known which resemble single-cell green algae, but definitive identity with that group of algae is uncertain.
The oldest known fossils of embryophytes date from the
OrdovicianThe Ordovician is a geologic period and system, the second of six of the Paleozoic era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian period and is followed by the Silurian period...
, though such fossils are fragmentary. By the
SilurianThe Silurian is a geologic period and system that extends from the end of the Ordovician period, about 443.7 ± 1.5 Ma , to the beginning of the Devonian period, about 416.0 ± 2.8 Ma . As with other geologic periods, the rock beds that define the period's start and end are well identified, but the...
, fossils of whole plants are preserved, including the lycophyte
Baragwanathia longifolia. From the Devonian, detailed fossils of rhyniophytes have been found. Early fossils of these ancient plants show the individual cells within the plant tissue. The Devonian period also saw the evolution of what many believe to be the first modern tree,
ArchaeopterisArchaeopteris is an extinct genus of tree-like plants with fern-like leaves. A useful index fossil, this tree is found in strata dating from the Upper Devonian to Lower Carboniferous, and has a global distribution....
. This fern-like tree combined a woody trunk with the fronds of a fern, but produced no seeds.
The
Coal measureThe Coal Measures is a lithostratigraphical term used mainly in the British Isles for the coal-bearing part of the Upper Carboniferous System. It represents the remains of fluvio-deltaic sediment, and consists mainly of clastic rocks interstratified with the beds of coal...
s are a major source of
PaleozoicThe Paleozoic or Palaeozoic Era is the earliest of three geologic eras of the Phanerozoic eon...
plant fossils, with many groups of plants in existence at this time. The spoil heaps of coal mines are the best places to collect;
coalCoal is a readily combustible black or brownish-black sedimentary rock normally occurring in rock strata in layers or veins called coal beds. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
itself is the remains of fossilised plants, though structural detail of the plant fossils is rarely visible in coal. In the Fossil Forest at Victoria Park in
GlasgowGlasgow is the largest city in Scotland and third most populous in the United Kingdom. The city is situated on the River Clyde in the country's west central lowlands...
,
ScotlandScotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
, the stumps of
LepidodendronLepidodendron is an extinct genus of primitive, vascular, arborescent plant related to the Lycopsids . It was part of the coal forest flora. They sometimes reached heights of over , and the trunks were often over in diameter, and thrived during the Carboniferous period...
trees are found in their original growth positions.
The fossilized remains of conifer and angiosperm
rootIn vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...
s,
stemsA stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , cones or other stems etc. The internodes act as spaces that distance one node from another...
and
branchA branch or tree branch is a woody structural member connected to but not part of the central trunk of a tree...
es may be locally abundant in lake and inshore
sedimentary rockSedimentary rock is the type of rock that is formed by sedimentation of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....
s from the
MesozoicThe Mesozoic Era is one of three geologic eras of the Phanerozoic eon. The division of time into eras dates back to Giovanni Arduino, in the 18th century, although his original name for the era now called the "Mesozoic" was "Secondary" The Mesozoic Era is one of three geologic eras of the...
and
CenozoicThe Cenozoic Era The Cenozoic (also Cænozoic or Cainozoic) Era The Cenozoic (also Cænozoic or Cainozoic) Era (meaning "new life" (Greek (kainos), "new", and (zoe), "life"), is the most recent of the three classic geological eras and covers the period from 65.5 million years ago to the...
eras. Sequoia and its allies,
magnoliaMagnolia is a large genus of about 210 flowering plant species in the subclass Magnolioideae of the family Magnoliaceae.The natural range of Magnolia species is a disjunct distribution, with a main center in east and southeast Asia and a secondary center in eastern North America, Central America,...
,
oakAn oak is a tree or shrub in the genus Quercus , of which about 400 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
, and
palmsArecaceae or Palmae , the palm family, is a family of flowering plants, the only family in the monocot order Arecales...
are often found.
Petrified woodPetrified wood is a type of fossil: it consists of fossil wood where all the organic materials have been replaced with minerals , while retaining the original structure of the wood...
is common in some parts of the world, and is most frequently found in arid or desert areas where it is more readily exposed by
erosionErosion is a gravity driven process that moves solids in the natural environment or their source and deposits them elsewhere...
. Petrified wood is often heavily silicified (the organic material replaced by
silicon dioxideThe chemical compound silicon dioxide, also known as silica , is an oxide of silicon with a chemical formula of ' and has been known for its hardness since antiquity. Silica is most commonly found in nature as sand or quartz, as well as in the cell walls of diatoms...
), and the impregnated tissue is often preserved in fine detail. Such specimens may be cut and polished using
lapidaryA lapidary is an artist or artisan who forms stone, mineral, gemstones, and other suitably durable materials into decorative items such as engraved gems including cameos, or cabochons, and faceted designs...
equipment. Fossil forests of petrified wood have been found in all continents.
Fossils of seed ferns such as
GlossopterisGlossopteris is the largest and best-known genus of the extinct order of seed ferns known as Glossopteridales ....
are widely distributed throughout several continents of the
Southern HemisphereThe Southern Hemisphere is the half of a planet that is south of the equator—the word hemisphere literally means 'half ball'...
, a fact that gave support to
Alfred WegenerAlfred Lothar Wegener was a German scientist, geologist, and meteorologist.He is most notable for his theory of continental drift , proposed in 1915, which hypothesized that the continents were slowly drifting around the Earth...
's early ideas regarding
Continental driftContinental drift is the movement of the Earth's continents relative to each other. The hypothesis that continents 'drift' was first put forward by Abraham Ortelius in 1596 and was fully developed by Alfred Wegener in 1912...
theory.
Structure, growth, and development
Most of the solid material in a plant is taken from the atmosphere. Through a process known as
photosynthesisPhotosynthesis is a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of Bacteria, but not in Archaea...
, most plants use the energy in
sunlightSunlight, in the broad sense, is the total spectrum of the electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the atmosphere, and the solar radiation is obvious as daylight when the Sun is above the horizon. Near the poles in summer, the days are longer and the...
to convert
carbon dioxideCarbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state...
from the atmosphere, plus
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
, into simple
sugarSugar is a class of edible crystalline substances, mainly sucrose, lactose, and fructose. Human taste buds interpret its flavor as sweet. Sugar as a basic food carbohydrate primarily comes from sugar cane and from sugar beet, but also appears in fruit, honey, sorghum, sugar maple , and in many...
s.
Parasitic plantA parasitic plant is one that derives some or all of its sustenance from another plant. About 4,100 species in approximately 19 families of flowering plants are known. Parasitic plants have a modified root, the haustorium, that penetrates the host plant and connects to the xylem, phloem, or both....
s, on the other hand, use the resources of its host to grow. These sugars are then used as building blocks and form the main structural component of the plant.
ChlorophyllChlorophyll is a green pigment found in most plants, algae, and cyanobacteria. Its name is derived from the Greek χλωρός and φύλλον...
, a green-colored,
magnesiumMagnesium is a chemical element with the symbol Mg, atomic number 12 and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the earth's crust by mass, although ninth in the Universe as a whole...
-containing
pigmentA pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
is essential to this process; it is generally present in plant
leavesIn botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin. There is continued debate about whether the flatness of leaves evolved to expose the chloroplasts to more light or to increase the absorption of carbon dioxide. In...
, and often in other plant parts as well.
Plants usually rely on soil primarily for support and water (in quantitative terms), but also obtain
compoundsA chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
of
nitrogenNitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere.Many industrially important...
,
phosphorusPhosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate rocks. Elemental phosphorus exists in two major forms - white phosphorus and red phosphorus...
, and other crucial elemental nutrients.
EpiphyticAn epiphyte is:Epiphyte is one of the subdivisions of the Raunkiær system. The term most commonly refers to higher plants, but epiphytic bacteria, fungi , algae, lichens, mosses, and ferns exist as well. The term epiphytic derives from the Greek epi- and phyton...
and
lithophyticLithophytes are a type of plant that grows in or on rocks. Lithophytes feed off moss, nutrients in rain water, litter, and even their own dead tissue....
plants often depend on rainwater or other sources for nutrients and
carnivorous plantCarnivorous plants are plants that derive some or most of their nutrients from trapping and consuming animals or protozoans, typically insects and other arthropods. Carnivorous plants appear adapted to grow in places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic...
s supplement their nutrient requirements with insect prey that they capture. For the majority of plants to grow successfully they also require
oxygenOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
in the atmosphere and around their roots for
respirationThe air space in soil contains oxygen to provide for respiration of plant roots and soil organisms. This air space could also contain carbon dioxide as a product of respiration of plant roots and soil organisms.Composition of air in soil and atmosphere:...
. However, some plants grow as submerged aquatics, using oxygen dissolved in the surrounding water, and a few specialized vascular plants, such as
mangroveMangroves are trees and shrubs that grow in saline coastal habitats in the tropics and subtropics – mainly between latitudes N and S. The saline conditions tolerated by various species range from brackish water, through pure seawater , to water of over twice the salinity of ocean seawater,...
s, can grow with their roots in anoxic conditions.
Factors affecting growth
The genotype of a plant affects its growth, for example selected varieties of wheat grow rapidly, maturing within 110 days, whereas others, in the same environmental conditions, grow more slowly and mature within 155 days.
Growth is also determined by environmental factors, such as
temperatureIn physics, temperature is a physical property of a system that underlies the common notions of hot and cold; something that feels hotter generally has the higher temperature. Temperature is one of the principal parameters of thermodynamics...
, available
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
, available
lightLight is electromagnetic radiation, particularly radiation of a wavelength that is visible to the human eye ....
, and available
nutrientA nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment. Nutrients are the substances that enrich the body. They build and repair tissues, give heat and energy, and regulate body processes...
s in the soil. Any change in the availability of these external conditions will be reflected in the plants growth.
Biotic factors are also capable of affecting plant growth. Plants compete with other plants for space, water, light and nutrients. Plants can be so crowded that no single individual produces normal growth. Optimal plant growth can be hampered by grazing animals, suboptimal soil composition, lack of
mycorrhizaA mycorrhiza is a symbiotic association between a fungus and the roots of a plant. In a mycorrhizal association, the fungus may colonize the roots of a host plant, either intracellularly or extracellularly...
l fungi, and attacks by insects or plant diseases, including those caused by bacteria, fungi, viruses, and nematodes.
Simple plants like algae may have short life spans as individuals, but their populations are commonly seasonal. Other plants may be organized according to their seasonal growth pattern:
annual plantAn annual plant is a plant that usually germinates, flowers, and dies in a year or season. True annuals will only live longer than a year if they are prevented from setting seed...
s live and reproduce within one
growing seasonIn agriculture, the growing season is the period of each year when crops can be grown. It is usually determined by climate and crop selection. Depending on the location, temperature, daylight hours , and rainfall, may all be critical environmental factors.In the northern U.S...
,
biennial plantA biennial plant is a flowering plant that takes two years to complete its biological lifecycle. In the first year the plant grows leaves, stems, and roots , then it enters a period of dormancy over the colder months. Usually the stem remains very short and the leaves are low to the ground, forming...
s live for two growing seasons and usually reproduce in second year, and
perennial plantA perennial plant or perennial is a plant that lives for more than two years. When used by gardeners or horticulturalists, this term applies specifically to perennial herbaceous plants...
s live for many growing seasons and continue to reproduce once they are mature. These designations often depend on climate and other environmental factors; plants that are annual in
alpineAlpine climate is the average weather for a region above the tree line. The climate becomes colder at high elevations—this characteristic is described by the lapse rate of air: air tends to get colder as it rises, since it expands. The dry adiabatic lapse rate is 10 °C per km of...
or
temperateIn geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally mild, rather than extreme hot or cold. But in continental areas, such as central North America the variations between summer...
regions can be biennial or perennial in warmer climates. Among the vascular plants, perennials include both
evergreenIn botany, an evergreen plant is a plant having leaves all year round. This contrasts with deciduous plants, which completely lose their foliage for part of the year....
s that keep their leaves the entire year, and
deciduousDeciduous means falling off at maturity or tending to fall off and is typically used in reference to trees or shrubs that lose their leaves seasonally and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
plants which lose their leaves for some part of it. In temperate and boreal climates, they generally lose their leaves during the winter; many tropical plants lose their leaves during the
dry seasonThe dry season is a term commonly used when describing the weather in the tropics. The weather in the tropics is dominated by the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year...
.
The growth rate of plants is extremely variable. Some mosses grow less than 0.001 millimeters per hour (mm/h), while most trees grow 0.025-0.250 mm/h. Some climbing species, such as
kudzuKudzu, Pueraria lobata is one of about 20 species in the genus Pueraria in the pea family Fabaceae, subfamily Faboideae. It is a climbing, coiling, and trailing vine native to southern Japan and southeast China...
, which do not need to produce thick supportive tissue, may grow up to 12.5 mm/h.
Plants protect themselves from
frostFrost is the solid deposition of water vapor from saturated air. It is formed when solid surfaces are cooled to below the dew point of the adjacent air. Frost crystals' size differ depending on time and water vapor available. Frost is also usually translucent in appearance. There are many types of...
and
dehydrationDehydration is defined as excessive loss of body water. It is literally the removal of water from an object. In physiological terms, it entails a relative deficiency of water molecules in relation to other dissolved solutes...
stress with
antifreeze proteinAntifreeze proteins or ice structuring proteins refer to a class of polypeptides produced by certain vertebrates, plants, fungi and bacteria that permit their survival in subzero environments. AFPs bind to small ice crystals to inhibit growth and recrystallization of ice that would otherwise be...
s,
heat-shock proteinsHeat shock proteins are a class of functionally related proteins whose expression is increased when cells are exposed to elevated temperatures or other stress. This increase in expression is transcriptionally regulated. The dramatic upregulation of the heat shock proteins is a key part of the...
and sugars (
sucroseSucrose, commonly called table sugar, is a moosaccharide of glucose and fructose with the molecular formula C12H22O11. This white, odorless, crystalline powder has a pleasing, sweet taste. It is best known for its role in human nutrition...
is common). LEA (Late
EmbryogenesisEmbryogenesis is the process by which the embryo is formed and develops. It starts with the fertilization of the ovum which, after fertilization, is referred to as a zygote. The zygote undergoes rapid mitotic divisions with no significant growth and cellular differentiation, leading to...
Abundant) protein expression is induced by stresses and protects other proteins from aggregation as a result of
desiccationDesiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic substance that induces or sustains such a state in its local vicinity in a moderately-well sealed container.-Science:-Desiccator:...
and
freezingIn physical science, freezing or solidification is the process in which a liquid turns into a solid when cold enough. The freezing point is the temperature at which this happens. Melting, the process of turning a solid to a liquid, is almost the exact opposite of freezing...
.
Plant cell
Plant cells are typically distinguished by their large water-filled central
vacuolethumb|400px|Plant cell structurethumb|400px|Animal cell structureA vacuole is a membrane organelle which is present in all plant and fungal cells and some protist, animal and bacterial cells...
,
chloroplastChloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.The word chloroplast is...
s, and rigid
cell wallA cell wall is a tough, flexible and sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to act as a...
s that are comprised of
celluloseCellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
,
hemicelluloseA hemicellulose can be any of several heteropolymers present in almost all plant cell walls along with cellulose. While cellulose is crystalline, strong, and resistant to hydrolysis, hemicellulose has a random, amorphous structure with little strength...
, and
pectinPectin is a structural heteropolysaccharide contained in the primary cell walls of terrestrial plants. It was first isolated and described in 1825 by Henri Braconnot...
.
Cell divisionCell division is a process by which a cell, called the parent cell, divides into two or more cells, called daughter cells. Cell division is usually a small segment of a larger cell cycle. This type of cell division in eukaryotes is known as mitosis, and leaves the daughter cell capable of dividing...
is also characterized by the development of a
phragmoplastthumb|300px|Phragmoplast and cell plate formation in a plant cell during cytokinesis. Left side: Phragmoplast forms and cell plate starts to assemble in the center of the cell. Towards the right: Phragmoplast enlarges in a donut-shape towards the outside of the cell, leaving behind mature cell...
for the construction of a
cell platethumb|300px|Phragmoplast and cell plate formation in a plant cell during cytokinesis. Left side: Phragmoplast forms and cell plate starts to assemble in the center of the cell. Toawards the right: Phragmoplast enlarges in a donut-shape towards the outside of the cell, leaving behind mature cell...
in the late stages of
cytokinesisCytokinesis is the process in which the cytoplasm of a single eukaryotic cell is divided to form two daughter cells. It usually initiates during the late stages of mitosis, and sometimes meiosis, splitting a binucleate cell in two, to ensure that chromosome number is maintained from one generation...
. Just as in animals, plant cells differentiate and develop into multiple cell types. Totipotent
meristemA meristem is the tissue in all plants consisting of undifferentiated cells and found in zones of the plant where growth can take place....
atic cells can differentiate into
vascularVascular tissue is a complex conducting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem. These two tissues transport fluid and nutrients internally. There are also two meristems associated with vascular tissue:...
, storage, protective (e.g.
epidermal layerThe epidermis is a single-layered group of cells that covers plants leaves, flowers, roots and stems. It forms a boundary between the plant and the external world. The epidermis serves several functions, it protects against water loss, regulates gas exchange, secretes metabolic compounds, and ...
), or
reproductivePlant sexuality covers the wide variety of sexual reproduction systems found across the plant kingdom. This article describes morphological aspects of sexual reproduction of plants....
tissues, with more primitive plants lacking some tissue types.
Photosynthesis
Plants are
photosyntheticPhotosynthesis is a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of Bacteria, but not in Archaea...
, which means that they manufacture their own food molecules using energy obtained from
lightLight is electromagnetic radiation, particularly radiation of a wavelength that is visible to the human eye ....
. The primary mechanism plants have for capturing light energy is the
pigmentA pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
chlorophyllChlorophyll is a green pigment found in most plants, algae, and cyanobacteria. Its name is derived from the Greek χλωρός and φύλλον...
. All green plants contain two forms of chlorophyll, chlorophyll
a and chlorophyll
b. The latter of these pigments is not found in red or brown algae.
Internal distribution
Vascular plantVascular plants are those plants that have lignified tissues for conducting water, minerals, and photosynthetic products through the plant. Vascular plants include the ferns, clubmosses, flowering plants, conifers and other gymnosperms...
s differ from other plants in that they transport nutrients between different parts through specialized structures, called
xylemIn vascular plants, xylem is one of the two types of transport tissue, phloem being the other. The word "xylem" is derived from classical Greek ξυλον , "wood", and indeed the best-known xylem tissue is wood, though it is found throughout the plant...
and
phloemIn vascular plants, phloem is the living tissue that carries organic nutrients , particularly sucrose, a sugar, to all parts of the plant where needed. In trees, the phloem is the innermost layer of the bark, hence the name, derived from the Greek word "bark"...
. They also have
rootIn vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...
s for taking up water and minerals. The xylem moves water and minerals from the root to the rest of the plant, and the phloem provides the roots with sugars and other nutrient produced by the leaves.
Ecology
The photosynthesis conducted by land plants and algae is the ultimate source of energy and organic material in nearly all ecosystems. Photosynthesis radically changed the composition of the early Earth's atmosphere, which as a result is now 21%
oxygenOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
. Animals and most other organisms are
aerobicAn aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment. -Types:*Obligate aerobes require oxygen for aerobic cellular respiration...
, relying on oxygen; those that do not are confined to relatively rare anaerobic environments. Plants are the
primary producersAn autotroph is an organism that produces complex organic compounds from simple inorganic molecules using energy from light or inorganic chemical reactions....
in most terrestrial ecosystems and form the basis of the food web in those ecosystems. Many animals rely on plants for shelter as well as oxygen and food.
Land plants are key components of the
water cycleThe water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above and below the surface of the Earth. Since the water cycle is truly a "cycle," there is no beginning or end. Water can change states among liquid, vapor, and ice at various places in the water...
and several other
biogeochemical cycleIn ecology and Earth science, a biogeochemical cycle or nutrient cycle is a pathway by which a chemical element or molecule moves through both biotic and abiotic compartments of Earth...
s. Some plants have coevolved with
nitrogen fixingNitrogen fixation usually refers to the biological process by which nitrogen in the atmosphere is converted into ammonia. This process is essential for life because fixed nitrogen is required to biosynthesize a basic building block of life, e.g. nucleotides for DNA and amino acids for proteins...
bacteria, making plants an important part of the
nitrogen cycleNitrogen is the most abundant element in the atmosphere and is essential to all life. The nitrogen cycle is the biogeochemical cycle that describes the transformations of nitrogen and nitrogen-containing compounds in nature. It is a cycle that includes gaseous components.Earth's atmosphere is...
. Plant roots play an essential role in
soilSoil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics. It is composed of particles of broken rock that have been altered by chemical and...
development and prevention of soil erosion.
Distribution
Plants are distributed worldwide in varying numbers. While they inhabit a multitude of
biomeBiome are climatically and geographically defined areas of ecologically similar climatic conditions such as communities of plants, animals, and soil organisms, and are often referred to as ecosystems...
s and
ecoregionAn ecoregion , sometimes called a bioregion, is an ecologically and geographically defined area smaller than a "realm" or "ecozone". Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural communities and species...
s, few can be found beyond the
tundraIn physical geography, tundra is a biome where the tree growth is hindered by low temperatures and short growing seasons. The term tundra comes from Kildin Sami tūndâr, which means "uplands, treeless mountain tract." There are two types of tundra: Arctic tundra and alpine tundra...
s at the northernmost regions of
continental shelvesThe continental shelf is the extended perimeter of each continent and associated coastal plain, and was part of the continent during the glacial periods, but is undersea during interglacial periods such as the current epoch by relatively shallow seas and gulfs. The continental rise is below the...
. At the southern extremes, plants have adapted tenaciously to the prevailing conditions. (See
Antarctic floraThe Antarctic flora is a distinct community of vascular plants which evolved millions of years ago on the supercontinent of Gondwana, and is now found on several separate areas of the Southern Hemisphere, including southern South America, southernmost Africa, New Zealand, Australia and New Caledonia...
.)
Plants are often the dominant physical and structural component of habitats where they occur. Many of the Earth's
biomeBiome are climatically and geographically defined areas of ecologically similar climatic conditions such as communities of plants, animals, and soil organisms, and are often referred to as ecosystems...
s are named for the type of vegetation because plants are the dominant organisms in those biomes, such as
grasslandGrasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...
s and
forestA forest is an area with a high density of trees. There are many definitions of a forest, based on the various criteria. These plant communities presently cover approximately 9.4% of the Earth's surface in many different regions and function as habitats for organisms, hydrologic flow modulators,...
s.
Ecological relationships
Numerous animals have coevolved with plants. Many animals pollinate
flowerA flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to mediate the union of male sperm with female ovum in order to produce seeds...
s in exchange for food in the form of pollen or nectar. Many animals
disperse seedsBiological dispersal refers to a species movement away from an existing population or away from the parent organism. Through simply moving from one habitat patch to another, the dispersal of an individual has consequences not only for individual fitness, but also for population dynamics, population...
, often by eating
fruitThe term fruit has different meanings dependent on context, and the term is not synonymous in food preparation and biology. Fruits are the means by which flowering plants disseminate seeds, and the presence of seeds indicates that a structure is most likely a fruit, though not all seeds come from...
and passing the seeds in their
fecesFeces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus during defecation.-Etymology:...
.
MyrmecophyteA myrmecophyte or ant plant is a plant that lives in association with a colony of ants and possesses specialized organs in which the ants live....
s are plants that have coevolved with
antAnts are social insects of the family Formicidae , and along with the related wasps and bees, they belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants...
s. The plant provides a home, and sometimes food, for the ants. In exchange, the ants defend the plant from
herbivoreA herbivore is an animal that is adapted to eat plants and not meat.Herbivory is a form of predation in which an organism consumes principally autotrophs such as plants, algae and photosynthesizing bacteria....
s and sometimes competing plants. Ant wastes provide organic
fertilizerFertilizers are chemical compounds applied to promote plant and fruit growth. Fertilizers are usually applied either through the soil or by foliar feeding...
.
The majority of plant species have various kinds of fungi associated with their root systems in a kind of mutualistic
symbiosisThe term symbosis commonly describes close and often long-term interactions between different biological species...
known as
mycorrhizaA mycorrhiza is a symbiotic association between a fungus and the roots of a plant. In a mycorrhizal association, the fungus may colonize the roots of a host plant, either intracellularly or extracellularly...
. The fungi help the plants gain water and mineral nutrients from the soil, while the plant gives the fungi carbohydrates manufactured in photosynthesis. Some plants serve as homes for
endophyticAn endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life without causing apparent disease. Endophytes are ubiquitous and have been found in all the species of plants studied to date; however, most of these endophyte/plant relationships...
fungi that protect the plant from herbivores by producing toxins. The fungal endophyte,
Neotyphodium coenophialumNeotyphodium coenophialum is a systemic and seed-transmissible symbiont of Lolium arundinaceum , a grass endemic to Eurasia and North Africa, but widely naturalized in North America, Australia and New Zealand / Aotearoa...
, in tall fescue (
Festuca arundinacea) does tremendous economic damage to the cattle industry in the U.S.
Various forms of parasitism are also fairly common among plants, from the semi-parasitic
mistletoeMistletoe is the common name for a group of hemi-parasitic plants in the order Santalales that grow attached to and within the branches of a tree or shrub...
that merely takes some nutrients from its host, but still has photosynthetic leaves, to the fully parasitic
broomrapeBroomrape or Broom-rape is a genus of about 150 species of parasitic herbaceous plants in the family Orobanchaceae, mostly native to the temperate Northern Hemisphere. Some species formerly included in this genus are now referred to the genus Conopholis.The broomrape plant is small, from 10-60 cm...
and
toothwortToothwort is a small genus of five to seven species of flowering plants, native to temperate Europe and Asia. They are parasites on the roots of other plants, and are completely lacking chlorophyll. They are classified in the family Orobanchaceae...
that acquire all their nutrients through connections to the roots of other plants, and so have no
chlorophyllChlorophyll is a green pigment found in most plants, algae, and cyanobacteria. Its name is derived from the Greek χλωρός and φύλλον...
. Some plants, known as myco-heterotrophs, parasitize mycorrhizal fungi, and hence act as epiparasites on other plants.
Many plants are
epiphyteAn epiphyte is:Epiphyte is one of the subdivisions of the Raunkiær system. The term most commonly refers to higher plants, but epiphytic bacteria, fungi , algae, lichens, mosses, and ferns exist as well. The term epiphytic derives from the Greek epi- and phyton...
s, meaning they grow on other plants, usually trees, without parasitizing them. Epiphytes may indirectly harm their host plant by intercepting mineral nutrients and light that the host would otherwise receive. The weight of large numbers of epiphytes may break tree limbs.
HemiepiphyteA hemiepiphyte is a plant which begins its life as an epiphyte but which later grows roots down into the ground. The seeds of hemiepiphytes germinate in the canopy and initially live epiphytically...
s like the
strangler figStrangler Fig is the common name for a number of tropical plant species, including some banyans and unrelated vines, namely:* Ficus aurea, also known as the Florida Strangler Fig* Ficus barbata, also known as the Bearded Fig* Ficus watkinsiana...
begin as epiphytes but eventually set their own roots and overpower and kill their host. Many orchids, bromeliads,
fernA fern is any one of a group of about 20,000 species of plants classified in the phylum or division Pteridophyta, also known as Filicophyta. The group is also referred to as Polypodiophyta, or Polypodiopsida when treated as a subdivision of tracheophyta...
s and
mossMosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...
es often grow as epiphytes. Bromeliad epiphytes accumulate water in leaf axils to form phytotelmata, complex aquatic food webs.
Approximately 630 plants are
carnivorousCarnivorous plants are plants that derive some or most of their nutrients from trapping and consuming animals or protozoans, typically insects and other arthropods. Carnivorous plants appear adapted to grow in places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic...
, such as the
Venus FlytrapThe Venus Flytrap, Dionaea muscipula, is a carnivorous plant that catches and digests animal prey—mostly insects and arachnids. Its trapping structure is formed by the terminal portion of each of the plant's leaves and is triggered by tiny hairs on their inner surfaces...
(
Dionaea muscipula) and
sundewDrosera, commonly known as the sundews, comprise one of the largest genera of carnivorous plants, with at least 188 species. These members of the family Droseraceae lure, capture, and digest insects using stalked mucilaginous glands covering their leaf surface...
(
Drosera species). They trap small animals and digest them to obtain mineral nutrients, especially
nitrogenNitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere.Many industrially important...
and
phosphorusPhosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate rocks. Elemental phosphorus exists in two major forms - white phosphorus and red phosphorus...
.
Importance
The study of plant uses by people is termed economic botany or
ethnobotany'The study and culture of plants'.Ethnobotany is the scientific study of the relationships that exist between people and plants....
; some consider economic botany to focus on modern cultivated plants, while ethnobotany focuses on indigenous plants cultivated and used by native peoples. Human cultivation of plants is part of
agricultureAgriculture is the production of food and goods through farming and forestry. Agriculture was the key development that led to the rise of human civilization, with the husbandry of domesticated animals and plants creating food surpluses that enabled the development of more densely populated and...
, which is the basis of human civilization. Plant agriculture is subdivided into
agronomyAgronomy is the science and technology of using plants for food, fuel, feed, and fiber. Agronomy encompasses work in the areas of plant genetics, plant physiology, meteorology, and soil science. Agronomy is the application of a combination of sciences like biology, chemistry, ecology, earth...
,
horticultureHorticulture is the industry and science of plant cultivation. Some would say that horticulture is the process of preparing soil for the planting of seeds, tubers, or cuttings. Horticulturists work and conduct research in the disciplines of plant propagation and cultivation, crop production, plant...
and
forestryForestry is the art and science of managing forests, tree plantations, and related natural resources. The main goal of forestry is to create and implement systems that allow forests to continue a sustainable continuation of environmental supplies and services...
.
Food
Much of human nutrition depends on land plants, either directly or indirectly.
Human nutrition depends to a large extent on
cerealCereals, grains or cereal grains, {as a collective} are grasses cultivated for the edible components of their fruit seeds - the endocarp, germ and bran...
s, especially
maizeMaize , is a herbaceous plant domesticated in Mesoamerica and subsequently spread throughout the American continents...
(or corn),
wheatWheat is a worldwide cultivated grass from the Fertile Crescent region of the Near East. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...
and
riceRice is the seed of a monocot plant Oryza sativa, of the grass family . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East, South, Southeast Asia, the Middle East, Latin America, and the West Indies...
. Other staple crops include
potatoThe potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well. In the region of the Andes, there are some other closely related cultivated potato species. Potatoes are the world's fourth largest food...
,
cassavaCassava is a woody shrub of the Euphorbiaceae native to South America that is extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy tuberous root, a major source of carbohydrates...
, and
legumeIn botanical writing legume is a plant in the family Fabaceae , or a fruit of these specific plants. A'legume' fruit is a simple dry fruit that develops from a simple carpel and usually dehisces on two sides. A common name for this type of fruit is a pod, although "pod" is also applied to a few...
s. Human food also includes
vegetableA vegetable is an edible plant or part of a plant. However, the word is not scientific, and its meaning is largely based on culinary and cultural tradition. Therefore the application of the word is somewhat arbitrary and subjective. For example, some people consider mushrooms to be vegetables,...
s,
spiceA spice is a dried seed, fruit, root, bark, leaf, or vegetative substance used in nutritionally insignificant quantities as a food additive for the purpose of flavour, colour, or as a preservative that kills harmful bacteria or prevents their growth....
s, and certain
fruitThe term fruit has different meanings dependent on context, and the term is not synonymous in food preparation and biology. Fruits are the means by which flowering plants disseminate seeds, and the presence of seeds indicates that a structure is most likely a fruit, though not all seeds come from...
s,
nutsNut is a general term for the large, dry, oily seeds or fruit of some plants. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be true nuts. Nuts are an important source of nutrients for both humans and...
,
herbA herb is a plant that is valued for flavor, scent, or other qualities. Herbs are used in cooking, as medicines, and for spiritual purposes....
s, and
edible flowersA flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to mediate the union of male sperm with female ovum in order to produce seeds...
.
Beverages produced from plants include
coffeeCoffee is a brewed beverage prepared from roasted seeds, commonly called coffee beans, of the coffee plant. They are seeds of "coffee cherries" that grow on trees in over 70 countries. It has been said that green coffee is the second most traded commodity in the world behind crude oil. Due to its...
,
teaTea is the agricultural product of the leaves, leaf buds, and internodes of the Camellia sinensis plant, prepared and cured by various methods...
,
wineWine is an alcoholic beverage typically made of fermented grape juice. The natural chemical balance of grapes is such that they can ferment without the addition of sugars, acids, enzymes or other nutrients. Wine is produced by fermenting crushed grapes using various types of yeast. Yeast consumes...
,
beerBeer is the world's oldest and most widely consumed alcoholic beverage and the third most popular drink overall after water and tea. It is produced by the brewing and fermentation of starches, mainly derived from cereal grains—most commonly malted barley, although wheat, maize , and rice are widely...
and
alcoholIn chemistry, an alcohol is any organic compound in which a hydroxyl group is bound to a carbon atom of an alkyl or substituted alkyl group. An important group of acohols is formed by the simple acyclic alcohols, the general formula for which is C
nH
2n+1OH...
.
SugarSugar is a class of edible crystalline substances, mainly sucrose, lactose, and fructose. Human taste buds interpret its flavor as sweet. Sugar as a basic food carbohydrate primarily comes from sugar cane and from sugar beet, but also appears in fruit, honey, sorghum, sugar maple , and in many...
is obtained mainly from sugar cane and
sugar beetSugar beet , a member of the Chenopodiaceae family, is a plant whose root contains a high concentration of sucrose. It is grown commercially for sugar production....
.
Cooking oilCooking oil is purified fat of plant origin, which is liquid at room temperature.Some of the many different kinds of edible vegetable oils include: olive oil, palm oil, soybean oil, canola oil, pumpkin seed oil, corn oil, sunflower oil, safflower oil, peanut oil, grape seed oil, sesame oil, argan...
s and
margarineMargarine , as a generic term, can indicate any of a wide range of butter substitutes. In many parts of the world, margarine has become the best-selling table spread, although butter and olive oil also command large market shares. Margarine is an ingredient in the preparation of many other foods...
come from maize,
soybeanThe soybean or soya bean is a species of legume native to East Asia. The plant is classed as an oilseed rather than a pulse. It is an annual plant that has been used in China for 5,000 years to primarily add nitrogen into the soil as part of crop rotation...
,
rapeseedRapeseed , also known as rape, oilseed rape, rapa, rapaseed and canola, is a bright yellow flowering member of the family Brassicaceae...
,
safflowerSafflower is a highly branched, herbaceous, thistle-like annual, usually with many long sharp spines on the leaves. Plants are 30 to 150 cm tall with globular flower heads and commonly, brilliant yellow, orange or red flowers which bloom in July. Each branch will usually have from one to...
,
sunflowerSunflowers are annual plants native to the Americas, that possess a large inflorescence .-Description :...
,
oliveThe Olive is a species of a small tree in the family Oleaceae, native to the coastal areas of the eastern Mediterranean Basin, from Lebanon, Syria and the maritime parts of Turkey and northern Iran at the south end of the Caspian Sea...
and others.
Food additiveFood additives are substances added to food to preserve flavour or improve its taste and appearance.Some additives have been used for centuries; for example, preserving food by pickling , salting, as with bacon, preserving sweets or using sulfur dioxide as in some wines...
s include
gum arabicGum arabic, also known as gum acacia, chaar gund, char goond or meska, is a natural gum made of hardened sap taken from two species of the acacia tree; Acacia senegal and Acacia seyal...
,
guar gumGuar gum, also called guaran, is a galactomannan. It is primarily the ground endosperm of guar beans. The guar seeds are dehusked, milled and screened to obtain the guar gum. It is typically produced as a free flowing, pale, off-white colored, coarse to fine ground powder.-Production:Guar gum is...
,
locust bean gumLocust bean gum is a galactomannan vegetable gum extracted from the seeds of the Carob tree. It is used as a thickening agent and gelling agent in food technology. It is soluble in hot water.Locust Bean Gum occurs as a white to yellow-white powder...
,
starchStarch or amylum is a polysaccharide carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds.Starch is produced by all green plants as an energy store and is a major food source for humans....
and
pectinPectin is a structural heteropolysaccharide contained in the primary cell walls of terrestrial plants. It was first isolated and described in 1825 by Henri Braconnot...
.
LivestockLivestock are one or more domesticated animals raised in an agricultural setting to produce commodities such as food or fiber, or labor...
animals including cows, pigs, sheep, and goats are all
herbivoreA herbivore is an animal that is adapted to eat plants and not meat.Herbivory is a form of predation in which an organism consumes principally autotrophs such as plants, algae and photosynthesizing bacteria....
s; and feed primarily or entirely on cereal plants, particularly
grassGrasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns...
es.
Nonfood products
WoodWood is an organic material; in the strict sense wood is produced as secondary xylem in the stems of trees . In a living tree it transfers water and nutrients to the leaves and other growing tissues, and has a support function, enabling woody plants to reach large sizes or to stand up for themselves...
is used for buildings, furniture, paper, cardboard, musical instruments and sports equipment. Cloth is often made from
cottonCotton is a soft, staple fiber that grows in a form known as a boll around the seeds of the cotton plant, a shrub native to tropical and subtropical regions around the world, including the Americas, India and Africa. The fiber most often is spun into yarn or thread and used to make a soft,...
,
flaxFlax is a member of the genus Linum in the family Linaceae. It is native to the region extending from the eastern Mediterranean to India and was probably first domesticated in the Fertile Crescent. This is called as Agasi/Akshi in Kannada, Jawas/Javas or Alashi in Marathi...
or synthetic fibers derived from
celluloseCellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
, such as
rayonRayon is a manufactured regenerated cellulose fiber. Because it is produced from naturally occurring polymers, it is neither a truly synthetic fiber nor a natural fiber; it is a semi-synthetic fiber. Rayon is known by the names viscose rayon and art silk in the textile industry. It usually has a...
and
acetateAn acetate, or ethanoate, is either a salt or ester of ethanoic acid.In chemistry, the abbreviation Ac refers to the acetyl group. The anion and the functional group may be written as −OAc and AcO−, or OAc respectively...
. Renewable fuels from plants include
firewoodFirewood is any wood like material that is gathered and used for fuel. Generally, firewood is not highly processed and is in some sort of recognizable log or branch form....
,
peatPeat is an accumulation of partially decayed vegetation matter. Peat forms in wetlandbogs, moors, muskegs, pocosins, mires, and peat swamp forests...
and many other
biofuelBiofuel is defined as solid, liquid or gaseous fuel obtained from lifeless or living biological material and is similar to fossil fuels, which are derived from long dead biological material. Also, various plants and plant-derived materials are used for biofuel manufacturing...
s.
CoalCoal is a readily combustible black or brownish-black sedimentary rock normally occurring in rock strata in layers or veins called coal beds. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
and
petroleumPetroleum or crude oil is a naturally occurring, flammable liquid found in rock formations in the Earth consisting of a complex mixture of hydrocarbons of various molecular weights, plus other organic compounds.The term "petroleum" was first used in the treatise De Natura Fossilium, published in...
are fossil fuels derived from plants. Medicines derived from plants include
aspirinAspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication....
, taxol,
morphineMorphine is a highly potent opiate analgesic psychoactive drug, is the principal active ingredient in Papaver somniferum , is considered to be the prototypical opioid. Like other opioids, e.g...
,
quinineQuinine is a natural white crystalline alkaloid having antipyretic , antimalarial, analgesic , and anti-inflammatory properties and a bitter taste. It is a stereoisomer of quinidine....
,
reserpineReserpine is an indole alkaloid antipsychotic and antihypertensive drug that has been used for the control of high blood pressure and for the relief of psychotic behaviors, although because of the development of better drugs for these purposes and because of its numerous side-effects, it is rarely...
,
colchicineColchicine is a toxic natural product and secondary metabolite, originally extracted from plants of the genus Colchicum . It was used originally to treat rheumatic complaints, especially gout, and still finds use for these purposes today. It was also prescribed for its cathartic and emetic effects...
,
digitalisDigitalis is a genus of about 20 species of herbaceous perennials, shrubs, and biennials that are commonly called foxgloves. The genus was traditionally placed in the figwort family Scrophulariaceae, but upon review of phylogenetic research, it has now been placed in the much enlarged family...
and
vincristineVincristine , also known as leurocristine, is a vinca alkaloid from the Catharanthus roseus , formerly Vinca rosea and hence its name. It is a mitotic inhibitor, and is used in cancer chemotherapy....
. There are hundreds of herbal supplements such as
ginkgoGinkgo , also known as the Maidenhair Tree after Adiantum, is a unique species of tree with no close living relatives...
,
EchinaceaEchinacea , is a genus of nine species of herbaceous plants in the family Asteraceae which are commonly called purple coneflowers. All are endemic to eastern and central North America, where they are found growing in moist to dry prairies and open wooded areas. They have large, showy heads of...
,
feverfewFeverfew is a traditional medicinal herb which is found in many old gardens, and is also occasionally grown for ornament. The plant grows into a small bush up to around high, with citrus-scented leaves and is covered by flowers reminiscent of daisies...
, and Saint John's wort.
PesticideA pesticide is a substance or mixture of substances used to kill a pest.A pesticide is any substance or mixture of substance intended for:- preventing, destroying, repelling or mitigating any pest....
s derived from plants include
nicotineNicotine is an alkaloid found in the nightshade family of plants which constitutes approximately 0.6–3.0% of dry weight of tobacco, with biosynthesis taking place in the roots, and accumulating in the leaves...
,
rotenoneRotenone is an odorless chemical that is used as a broad-spectrum insecticide, piscicide, and pesticide. It occurs naturally in the roots and stems of several plants such as the jicama vine plant. It causes Parkinson's disease-like symptoms if injected into rats...
,
strychnineStrychnine is a very toxic , colorless crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents. Strychnine causes muscular convulsions and eventually death through asphyxia or sheer exhaustion. The most common source is from the seeds of the...
and
pyrethrinThe pyrethrins are a pair of natural organic compounds that have potent insecticidal activity. Pyrethrin I and pyrethrin II are structurally related esters with a cyclopropane core. They differ by the oxidation state of one carbon. They are viscous liquids that oxidize to become inactivated. They...
s. Drugs obtained from plants include
opiumOpium is a narcotic formed from the latex released by lacerating the immature seed pods of opium poppies . It contains up to 12% morphine, an opiate alkaloid, which is most frequently processed chemically to produce heroin for the illegal drug trade...
,
cocaineCocaine is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. The name comes from "coca" in addition to the alkaloid suffix -ine, forming cocaine. It is a stimulant of the central nervous system and an appetite suppressant...
and
marijuanaCannabisalso known as marijuana or marihuana, and ganja , among many other namesrefers to any number of preparations of the Cannabis plant intended for use as a psychoactive drug...
. Poisons from plants include
ricinRicin is a protein that is extracted from the castor bean . It can be either a white powder or a liquid in crystalline form. Ricin is known to cause severe allergic reactions, and exposure to small quantities can be fatal.The U.S...
,
hemlockConium is a genus of two species of highly poisonous perennial herbaceous flowering plants in the family Apiaceae, native to Europe and the Mediterranean region , and to southern Africa ....
and
curareCurare is a common name for various arrow poisons originating from South America. The three main types of curare are:* tubocurare...
. Plants are the source of many natural products such as fibers,
essential oilAn essential oil is a concentrated, hydrophobic liquid containing volatile aroma compounds from plants. Essential oils are also known as volatile or ethereal oils, or simply as the "oil of" the plant from which they were extracted, such as oil of clove. An oil is "essential" in the sense that it...
s, dyes, pigments, waxes,
tanninTannins are astringent, bitter plant polyphenols that either bind and precipitate or shrink proteins. The astringency from the tannins is what causes the dry and puckery feeling in the mouth following the consumption of unripened fruit or red wine...
s,
latexLatex refers generically to a stable dispersion of polymer microparticles in an aqueous medium. Latexes may be natural or synthetic. Latex as found in nature is a milky sap-like fluid within many plants that coagulates on exposure to air. It is a complex emulsion in which proteins, alkaloids,...
,
gumsGum is a sap or other resinous material associated with certain species of the plant kingdom. This material is often polysaccharide-based and most frequently is associated with woody plants, particularly under the bark or as a seed coating...
,
resinResin is a hydrocarbon secretion of many plants, particularly coniferous trees. It is valued for its chemical constituents and uses, such as varnishes and adhesives, as an important source of raw materials for organic synthesis, or for incense and perfume. Fossilized resins are the source of amber...
s, alkaloids, amber and cork. Products derived from plants include soaps, paints, shampoos, perfumes, cosmetics, turpentine, rubber, varnish, lubricants, linoleum, plastics, inks, chewing gum and hemp rope. Plants are also a primary source of basic chemicals for the industrial synthesis of a vast array of organic chemicals. These chemicals are used in a vast variety of studies and experiments.
Aesthetic uses
Thousands of plant species are cultivated for aesthetic purposes as well as to provide shade, modify temperatures, reduce wind, abate noise, provide privacy, and prevent soil erosion. People use cut flowers, dried flowers and
houseplantA houseplant is a plant that is grown indoors in places such as residences and offices. Houseplants are commonly grown for decorative purposes and health reasons such as indoor air purification...
s indoors or in
greenhouseA greenhouse is a building where plants are cultivated.A greenhouse is a structure with a glass or plastic roof and frequently glass or plastic walls; it heats up because incoming solar radiation from the sun warms plants, soil, and other things inside the building faster than heat can escape the...
s. In outdoor
gardenA garden is a planned space, usually outdoors, set aside for the display, cultivation, and enjoyment of plants and other forms of nature. The garden can incorporate both natural and man-made materials. The most common form is known as a residential garden. Western gardens are almost universally...
s, lawn grasses, shade trees, ornamental trees, shrubs, vines, herbaceous perennials and bedding plants are used. Images of plants are often used in art, architecture, humor,
languageThe language of flowers, sometimes called floriography, was a Victorian-era means of communication in which various flowers and floral arrangements were used to send coded messages, allowing individuals to express feelings which otherwise could not be spoken...
, and photography and on textiles, money, stamps, flags and coats of arms. Living plant art forms include
topiaryTopiary is the art of creating sculptures in the medium of clipped trees, shrubs and sub-shrubs. The word derives from the Latin word for an ornamental landscape gardener, topiarius, creator of topia or "places", a Greek word that Romans applied also to fictive indoor landscapes executed in fresco...
,
bonsai' is the art of aesthetic miniaturization of trees, or of developing woody or semi-woody plants shaped as trees, by growing them in containers. Cultivation includes techniques for shaping, watering, and repotting in various styles of containers.'Bonsai' is a Japanese pronunciation of the earlier...
,
ikebanais the Japanese art of flower arrangement, also known as .More than simply putting flowers in a container, ikebana is a disciplined art form in which nature and humanity are brought together...
and
espalierEspalier is the horticultural technique of training trees through pruning and grafting in order to create formal "two-dimensional" or single plane patterns by the branches of the tree...
.
Ornamental plantOrnamental plants are typically grown in the flower garden or as house plants. Most commonly they are grown for the display of their flowers. Other common ornamental features include leaves, scent, fruit, stem and bark. In some cases, unusual features may be considered ornamental, such as the...
s have sometimes changed the course of history, as in tulipomania. Plants are the basis of a multi-billion dollar per year tourism industry which includes travel to
arboretumAn arboretum is a collection of trees. Related collections include a fruticetum , and a viticetum, a collection of vines. More commonly today, an arboretum is a botanical garden containing living collections of woody plants intended at least partly for scientific study...
s,
botanical gardenBotanical gardens grow a wide variety of plants primarily to categorize and document for scientific purposes. Botanists and horticulturalists tend the flora and maintain the garden's library and herbarium of dried and documented plant material. Botanical gardens may also serve to entertain and...
s,
historic gardensGarden tourism is a type of niche tourism involving visits or travel to botanical gardens and places which are significant in the history of gardening...
,
national parkA national park is a reserve of natural or semi-natural land, declared or owned by a national government, set aside for human recreation and enjoyment, and protected from most development...
s,
tulip festivalThe Tulip Festivals are held in several North American cities, most often ones with Dutch heritage, including Albany, New York; Ottawa, Ontario; Holland, Michigan; Orange City, Iowa; Pella, Iowa; Mount Vernon, Washington; and Woodburn, Oregon. The tulips are considered a welcome harbinger of...
s,
rainforestRainforests are forests characterized by high rainfall, with definitions setting minimum normal annual rainfall between 1750–2000 mm . The monsoon trough, alternately known as the intertropical convergence zone, plays a significant role in creating Earth's tropical rain forests.From 40 to 75%...
s,
forestA forest is an area with a high density of trees. There are many definitions of a forest, based on the various criteria. These plant communities presently cover approximately 9.4% of the Earth's surface in many different regions and function as habitats for organisms, hydrologic flow modulators,...
s with colorful autumn leaves and the
National Cherry Blossom FestivalThe National Cherry Blossom Festival is a spring celebration in Washington, D.C. commemorating the March 27, 1912, gift of Japanese cherry trees from Mayor Yukio Ozaki of Tokyo to the city of Washington...
.
Venus FlytrapThe Venus Flytrap, Dionaea muscipula, is a carnivorous plant that catches and digests animal prey—mostly insects and arachnids. Its trapping structure is formed by the terminal portion of each of the plant's leaves and is triggered by tiny hairs on their inner surfaces...
, sensitive plant and
resurrection plantA resurrection plant is any plant with the habit of reviving after seeming to be dead or, conversely, of seeming to revive when being in fact dead.Examples include...
are examples of plants sold as novelties.
Scientific and cultural uses
Tree rings are an important method of dating in archeology and serve as a record of past climates. Basic biological research has often been done with plants, such as the pea plants used to derive
Gregor MendelGregor Johann Mendel was an Augustinian priest and scientist, and is often called the father of genetics for his study of the inheritance of certain traits in pea plants. Mendel showed that the inheritance of these traits follows particular laws, which were later named after him...
's laws of genetics. Space stations or space colonies may one day rely on plants for
life supportControlled Ecological Life Support Systems are a type of scientific endeavor to create a self-supporting life support system for space stations and colonies typically through controlled closed ecological systems, such as the BioHome, BIOS-3 and Biosphere 2.-Original concept:CELSS was first...
. Plants are used as
nationalA national emblem symbolically represents a nation. Most national emblems originate in the natural world, such as animals or birds, but another object may serve....
and state emblems, including
state trees and state flowers. Ancient trees are revered and many are
famous. Numerous world records are held by plants. Plants are often used as memorials, gifts and to mark special occasions such as births, deaths, weddings and holidays. Plants figure prominently in mythology, religion and
literature. The field of
ethnobotany'The study and culture of plants'.Ethnobotany is the scientific study of the relationships that exist between people and plants....
studies plant use by indigenous cultures which helps to conserve endangered species as well as discover new
medicinal plantsHerbalism is a traditional medicinal or folk medicine practice based on the use of plants and plant extracts. Herbalism is also known as botanical medicine, medical herbalism, herbal medicine, herbology, and phytotherapy...
.
GardeningGardening is the practice of growing ornamental or useful plants. Ornamental plants are normally grown for their flowers, foliage, or overall appearance. Useful plants may be grown for consumption or for a variety of other purposes, such as medicines or dyes...
is the most popular leisure activity in the U.S. Working with plants or
horticulture therapyHorticultural therapy is the practice of horticulture as therapy to improve human well-being. According to the American Horticultural Therapy Association, HT is defined as “a process utilizing plants and horticultural activities to improve social, educational, psychological and physical adjustment...
is beneficial for rehabilitating people with disabilities. Certain plants contain psychotropic chemicals which are extracted and ingested, including
tobaccoTobacco is an agricultural product processed from the leaves of plants in the genus Nicotiana. It can be consumed, used as an organic pesticide, and in the form of nicotine tartrate it is used in some medicines. In consumption it most commonly appears in the forms of smoking, chewing, snuffing, or...
,
cannabisCannabisalso known as marijuana or marihuana, and ganja , among many other namesrefers to any number of preparations of the Cannabis plant intended for use as a psychoactive drug...
(marijuana), and
opiumOpium is a narcotic formed from the latex released by lacerating the immature seed pods of opium poppies . It contains up to 12% morphine, an opiate alkaloid, which is most frequently processed chemically to produce heroin for the illegal drug trade...
.
Negative effects
WeedA weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-made settings such as gardens, lawns or agricultural areas, but also in parks, woods and other natural areas. More specifically, the term is often...
s are plants that grow where people do not want them. People have spread plants beyond their native ranges and some of these introduced plants become
invasive'Invasive species' is a phrase with several definitions. The first definition expresses the phrase in terms of non-indigenous species that adversely affect the habitats they invade economically, environmentally or ecologically...
, damaging existing ecosystems by displacing native species. Invasive plants cause billions of dollars in crop losses annually by displacing crop plants, they increase the cost of production and the use of chemical means to control them affects the environment.
Plants may cause harm to people and animals. Plants that produce windblown pollen invoke allergic reactions in people who suffer from
hay feverHay Fever is a comic play written by Noël Coward in 1924 and first produced in 1925 with Marie Tempest as the first Judith Bliss.Laura Hope Crewes played the role in New York...
. A wide variety of plants are
poisonous to people and/or animals. Several plants cause skin irritations when touched, such as
poison ivyToxicodendron radicans is a plant in the family with 3 leaves Anacardiaceae. The name is sometimes spelled "Poison-ivy" in an attempt to indicate that the plant is not a true Ivy...
. Certain plants contain psychotropic
chemicalsSecondary metabolites are organic compounds that are not directly involved in the normal growth, development, or reproduction of organisms. Unlike primary metabolites, absence of secondary metabolities does not result in immediate death, but rather in long-term impairment of the organism's...
, which are extracted and ingested or smoked, including tobacco, cannabis (marijuana),
cocaineCocaine is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. The name comes from "coca" in addition to the alkaloid suffix -ine, forming cocaine. It is a stimulant of the central nervous system and an appetite suppressant...
and
opiumOpium is a narcotic formed from the latex released by lacerating the immature seed pods of opium poppies . It contains up to 12% morphine, an opiate alkaloid, which is most frequently processed chemically to produce heroin for the illegal drug trade...
, causing damage to health or even death. Both illegal and legal drugs derived from plants have negative effects on the economy, affecting worker productivity and law enforcement costs. Some plants cause allergic reactions in people and animals when ingested, while other plants cause food intolerances that negatively affect health.
See also
- Biosphere
The biosphere is the global sum of all ecosystems. It can also be called the zone of life on Earth. From the broadest biophysiological point of view, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements...
- Leaf sensor
A leaf sensor is a phytometric device that measures water loss or the water deficit stress in plants by real-time monitoring the moisture level in plant leaves. The first leaf sensor was developed by LeafSens, an Israeli company who were granted a US patent for a mechanical leaf thickness...
- Plant defense against herbivory
Plant defense against herbivory or host-plant resistance includes a range of adaptations evolved by plants that improve their survival and reproduction by reducing the impact of herbivores....
- Plant perception (paranormal)
In the study of paranormal phenomenon Plant perception, or biocommunication in plant cells, has come to mean a belief that plants are sentient, that they experience pain, pleasure, or emotions such as fear and affection, and that they have the ability to communicate with humans and other forms of...
- Plant perception (physiology)
In the study of plant physiology plant perception is a term used to describe mechanisms by which plants recognize changes in the environment. Examples of stimuli which plants perceive and can react to include chemicals, gravity, light, moisture, infections, temperature, oxygen and carbon dioxide...
- Rapid plant movement
Rapid plant movement encompasses movement in plant structures occurring over a very short period of time, usually under one second. For example, the Venus Flytrap closes its trap in about 100 milliseconds. The Dogwood Bunchberry's flower opens its petals and fires pollen in less than 0.5 milliseconds...
Further reading
General:
- Evans, L. T. (1998). Feeding the Ten Billion - Plants and Population
In biology, a population is the collection of inter-breeding organisms of a particular species; in sociology, a collection of human beings. Individuals within a population share a factor may be reduced by statistical means, but such a generalization may be too vague to imply anything...
Growth. Cambridge University PressCambridge University Press is a printer and publisher granted a Royal Letters Patent by Henry VIII in 1534. It is the world's oldest continually operating book publisher...
. Paperback, 247 pages. ISBN 0-521-64685-5.
- Kenrick, Paul & Crane, Peter R. (1997). The Origin and Early Diversification of Land Plants: A Cladistic Study. Washington, D. C.: Smithsonian Institution Press. ISBN 1-56098-730-8.
- Raven, Peter H., Evert, Ray F., & Eichhorn, Susan E. (2005). Biology of Plants (7th ed.). New York: W. H. Freeman and Company. ISBN 0-7167-1007-2.
- Taylor, Thomas N. & Taylor, Edith L. (1993). The Biology and Evolution of Fossil Plants. Englewood Cliffs, NJ: Prentice Hall. ISBN 0-13-651589-4.
- Trewavas, A. (2003). Aspects of Plant Intelligence, Annals of Botany 92: 1-20.
Species estimates and counts:
- International Union for Conservation of Nature and Natural Resources (IUCN) Species Survival Commission (2004). IUCN Red List
The IUCN Red List of Threatened Species , founded in 1948, is the world's most comprehensive inventory of the global conservation status of plant and animal species. The International Union for the Conservation of Nature and Natural Resources is the world's main authority on the conservation...
http://www.iucnredlist.org/.
- Prance, G. T. (2001). Discovering the Plant World. Taxon 50: 345-359.
External links
Botanical and vegetation databases