The
flowering plants or
angiosperms (
Angiospermae or
Magnoliophyta) are the most diverse group of land plants. The flowering plants and the gymnosperms are the only extant groups of
seed plantsThe spermatophytes comprise those plants that produce seeds. They are a subset of the embryophytes or land plants...
. The flowering plants are distinguished from other seed plants by a series of apomorphies, or derived characteristics.
Angiosperm derived characteristics
- Flower
A 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
The flowers, which are the reproductive organs of flowering plants, are the most remarkable feature distinguishing them from other seed plants. Flowers aid angiosperms by enabling a wider range of adaptability and broadening the
ecological nicheIn ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different school if the members of these schools utilize significantly different...
s open to them. This has allowed flowering plants to largely dominate terrestrial ecosystems.
- Stamen
The stamen is the male organ of a flower. Each stamen generally has a stalk called the filament , and, on top of the filament, an anther , and pollen sacs,...
s with two pairs of pollen sacs
Stamens are much lighter than the corresponding organs of gymnosperms and have contributed to the diversification of angiosperms through time with
adaptationAdaptation is the process whereby a population becomes better suited to its habitat. This process takes place over many generations, and is one of the basic phenomena of biology....
s to specialized
pollinationPollination is the process by which pollen is transferred in plants, thereby enabling fertilization and sexual reproduction. Pollen grains, which contain the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...
syndromes, such as particular pollinators. Stamens have also become modified through time to prevent self-fertilization, which has permitted further diversification, allowing angiosperms eventually to fill more niches.
- Reduced male parts, three cells
The male
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:...
in angiosperms is significantly reduced in size compared to those of gymnosperm seed plants. The smaller pollen decreases the time from pollination — the pollen grain reaching the female plant — to fertilization of the ovary; in gymnosperms fertilization can occur up to a year after pollination, while in angiosperms the fertilization begins very soon after pollination. The shorter time leads to angiosperm plants setting seeds sooner and faster than gymnosperms, which is a distinct evolutionary advantage.
- Closed carpel enclosing the ovules (carpel or carpels and accessory parts may become the fruit
The 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...
)
The closed carpel of angiosperms also allows adaptations to specialized pollination syndromes and controls. This helps to prevent self-fertilization, thereby maintaining increased diversity. Once the ovary is fertilized, the carpel and some surrounding tissues develop into a fruit. This fruit often serves as an attractant to seed-dispersing animals. The resulting cooperative relationship presents another advantage to angiosperms in the process of
dispersalBiological 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...
.
- Reduced female gametophyte, seven cells with eight nuclei
The reduced female gametophyte, like the reduced male gametophyte, may be an adaptation allowing for more rapid seed set, eventually leading to such flowering plant adaptations as annual herbaceous life cycles, allowing the flowering plants to fill even more niches.
- Endosperm
Endosperm is the tissue produced in the seeds of most flowering plants around the time of fertilization. It surrounds the embryo and provides nutrition in the form of starch, though it can also contain oils and protein. This makes endosperm an important source of nutrition in human diet...
Endosperm formation generally begins after fertilization and before the first division of the
zygoteA zygote , or zygocyte, is the initial cell formed when a new organism is produced by means of sexual reproduction. A zygote is synthesized from the union of two gametes, and constitutes the first stage in a unique organism's development...
. Endosperm is a highly nutritive tissue that can provide food for the developing
embryoAn embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
, the cotyledons, and sometimes for the
seedlingthumb|Monocot and dicot seedlingsA seedling is a young plant sporophyte developing out of a plant embryo from a seed. Seedling development starts with germination of the seed. A typical young seedling consists of three main parts: the radicle , the hypocotyl , and the cotyledons...
when it first appears.
These distinguishing characteristics taken together have made the angiosperms the most diverse and numerous land plants and the most commercially important group to humans. The major exception to the dominance of terrestrial ecosystems by flowering plants is the coniferous forest.
Evolution
Land plants have existed for about 425 million years. Early land plants
reproducedPlant sexuality covers the wide variety of sexual reproduction systems found across the plant kingdom. This article describes morphological aspects of sexual reproduction of plants....
sexually with flagellated, swimming sperm, like the green algae from which they evolved. An adaptation to terrestrialization was the development of upright meiosporangia for dispersal by
sporeIn biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions...
s to new habitats. This feature is lacking in the descendants of their nearest algal relatives, the Charophycean green algae. A later terrestrial adaptation took place with retention of the delicate, avascular sexual stage, the gametophyte, within the tissues of the vascular sporophyte. This occurred by spore germination within sporangia rather than spore release, as in non-seed plants. A current example of how this might have happened can be seen in the precocious spore germination in Sellaginella, the spike-moss. The result for the ancestors of angiosperms was enclosing them in a case, the
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...
. The first seed bearing plants, like the
ginkgoGinkgo , also known as the Maidenhair Tree after Adiantum, is a unique species of tree with no close living relatives...
, and conifers (such as
pinePines are coniferous trees in the genus Pinus , in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Distribution:...
s and
firFirs are a genus of between 48-55 species of evergreen conifers in the family Pinaceae. All are trees, reaching heights of 10-80 m tall and trunk diameters of 0.5-4 m when mature...
s), did not produce flowers. Interestingly, the pollen grains (males) of Ginkgo and cycads produce a pair of flagellated, mobile sperm cells that "swim" down the developiong pollen tube to the female and her eggs.
The apparently sudden appearance of relatively modern flowers in the fossil record posed such a problem for the theory of
evolutionIn biology, evolution is change in the genetic material of a population of organisms from one generation to the next. Though changes produced in any one generation are normally small, differences accumulate with each generation and can, over time, cause substantial changes in the population, a...
that it was called an "abominable mystery" by
Charles DarwinCharles Robert Darwin FRS was an English naturalist who realised and presented compelling evidence that all species of life have evolved over time from common ancestors, through the process he called natural selection...
. However, the fossil record has grown since the time of Darwin, and recently discovered angiosperm fossils such as
Archaefructus, along with further discoveries of fossil gymnosperms, suggest how angiosperm characteristics may have been acquired in a series of steps. Several groups of extinct gymnosperms, particularly seed ferns, have been proposed as the
ancestorsIn genetics, the most recent common ancestor of any set of organisms is the most recent individual from which all organisms in the group are directly descended...
of flowering plants but there is no continuous fossil evidence showing exactly how flowers evolved. Some older fossils, such as the upper
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...
Sanmiguelia, have been suggested. Based on current evidence, some propose that the ancestors of the angiosperms diverged from an unknown group of gymnosperms during the late
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...
(245–202 million years ago). A close relationship between angiosperms and gnetophytes, proposed on the basis of
morphologicalIn biology morphology is the form, structure and configuration of an organism.This includes aspects of the outward appearance as well as the form and structure of the internal parts like bones and organs...
evidence, has more recently been disputed on the basis of
molecular evidenceMolecular biology is the study of biology at a molecular level. The field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry...
that suggest gnetophytes are instead more closely related to other
gymnospermGymnosperm is a group of spermatophyte seed-bearing plants with ovules on scales, which are usually arranged in cone-like structures....
s.
The earliest known angiosperm
macrofossilMacrofossils are preserved organic remains large enough to be visible without a microscope. Most fossils discussed in the article Fossil are macrofossils.- Macrofossil contrasted with Microfossil :...
,
Archaefructus liaoningensisArchaefructus is an extinct genus of herbaceous aquatic seed plants with 3 known species. Fossil material assigned to this genus originates from the Yixian Formation in northeastern China, originally dated as late Jurassic but now thought to be approximately 125 million years old, or early...
, is dated to about 125 million years BP (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...
period), while pollen considered to be of angiosperm origin takes the
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...
record back to about 130 million years BP. There is, however, circumstantial chemical evidence for the existence of angiosperms as early as 250 million years ago.
OleananeOleananes is the name given to chemicals produced by many flowering plants, which have a suppressing effect on some insect pest organisms. Technically they are oleanane triterpanes....
, a
secondary metaboliteSecondary 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...
produced by many flowering plants, has been found in
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...]
deposits of that age together with fossils of
gigantopteridGigantopterids is the name given to fossils of a group of plants existing in the Late Permian, until some 250 million years ago. Gigantopterids were among the most advanced land plants of the Paleozoic and disappeared soon after the massive Permian–Triassic extinction event 251.4 million years ago...
s. Gigantopterids are a group of extinct seed plants that share many morphological traits with flowering plants, although they are not known to have been flowering plants themselves.
Recent
DNADeoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information...
analysis (molecular systematics) show that
Amborella trichopodaAmborella trichopoda is a rare, vesselless, understory shrub or small tree found only on the island of New Caledonia. It is of great interest in flora taxonomy because modern molecular phylogenetics data place it at or near the base of the flowering plants...
, found on the Pacific island of
New CaledoniaNew Caledonia , is a "sui generis collectivity" of France located in the region of Melanesia in the southwest Pacific. It comprises a main island , the Loyalty Islands, and several smaller islands...
, belongs to a sister group of the other flowering plants, and morphological studies suggest that it has features that may have been characteristic of the earliest flowering plants.
The great angiosperm
radiationAn adaptive radiation is a rapid evolutionary radiation characterized by an increase in the morphological and ecological diversity of a single, rapidly diversifying lineage. Phenotypes adapt in response to the environment, with new and useful traits arising...
, when a great diversity of angiosperms appears in the fossil record, occurred in the mid-
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...
(approximately 100 million years ago). However, a study in 2007 estimated that the division of the five most recent (the genus
CeratophyllumCeratophyllum is a cosmopolitan genus of flowering plants, commonly found in ponds, marshes, and quiet streams in tropical and in temperate regions...
, the family
ChloranthaceaeChloranthaceae is the botanical name of a family of flowering plants. The family consists of four genera, totalling several dozen species, of herbaceous or woody plants primarily occurring in the tropics and sub-tropics...
, the eudicots, the magnoliids, and the monocots) of the eight main groups occurred around 140 million years ago.
By the late Cretaceous, angiosperms appear to have become the predominant group of land plants, and many fossil plants recognizable as belonging to modern families (including
beechBeech is a genus of ten species of deciduous trees in the family Fagaceae, native to temperate Europe, Asia and North America.The leaves of beech trees are entire or sparsely toothed, from 5–15 cm long and 4–10 cm broad...
,
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...
,
mapleAcer is a genus of trees or shrubs commonly known as Maple. Maples are variously classified in a family of their own, the Aceraceae, or included in the family Sapindaceae. Modern classifications, including the Angiosperm Phylogeny Group classification, favour inclusion in Sapindaceae...
, and
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,...
) appeared.
It is generally assumed that the
functionA function is part of an answer to a question about why some object or process occurred in a system that evolved through a process of selection. Thus, function refers forward from the object or process, along some chain of causation, to the goal or success...
of flowers, from the start, was to involve mobile
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 in their reproduction processes. That is, pollen can be scattered even if the flower is not brightly
colorColor or colour is the visual perceptual property corresponding in humans to the categories called red, yellow, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...
ed or oddly shaped in a way that attracts animals; however, by expending the energy required to create such traits, angiosperms can enlist the aid of animals and thus reproduce more efficiently.
Island genetics provides one proposed explanation for the sudden, fully developed appearance of flowering plants. Island genetics is believed to be a common source of
speciationSpeciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...
in general, especially when it comes to radical adaptations that seem to have required inferior transitional forms. Flowering plants may have evolved in an isolated setting like an
islandAn island or isle is any piece of land that is surrounded by water. Very small islands such as emergent land features on atolls are called islets. A key or cay is another name for a small island or islet. An island in a river or lake may be called an eyot, .There are two main types of islands:...
or island chain, where the plants bearing them were able to develop a highly specialized relationship with some specific animal (a
waspThe term wasp is typically defined as any insect of the order Hymenoptera and suborder Apocrita that is neither a bee nor ant. Almost every pest insect species has at least one wasp species that preys upon it or parasitizes it, making wasps critically important in natural control of their numbers,...
, for example). Such a relationship, with a hypothetical wasp carrying pollen from one plant to another much the way
fig waspFig wasps are wasps of the family Agaonidae which pollinate figs or are otherwise associated with figs, a coevolutional relationship that has been developing for at least 80 million years....
s do today, could result in both the plant(s) and their partners developing a high degree of specialization. Note that the wasp example is not incidental; bees, which apparently evolved specifically due to mutualistic plant relationships, are descended from wasps.
Animals are also involved in the distribution of seeds.
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...
, which is formed by the enlargement of flower parts, is frequently a seed-dispersal tool that attracts animals to eat or otherwise disturb it, incidentally scattering the seeds it contains (see frugivory). While many such
mutualistic relationshipMutualism is a biological interaction between two organisms, where each individual derives a fitness benefit . Similar interactions within a species are known as co-operation...
s remain too fragile to survive
competitionCompetition can be defined as an Biological interaction structure. Competition among members of the same species is known as intraspecific competition, while competition between individuals of different species is known as interspecific competition...
and spread widely, flowering proved to be an unusually effective means of reproduction, spreading (whatever its origin) to become the dominant form of land plant life.
Flower
ontogenyOntogeny describes the origin and the development of an organism from the fertilized egg to its mature form...
uses a combination of
geneA gene is the basic unit of heredity in a living organism. All living things depend on genes. Genes hold the information to build and maintain their cells and pass genetic traits to offspring...
s normally responsible for forming new shoots. The most primitive flowers are thought to have had a variable number of flower parts, often separate from (but in contact with) each other. The flowers would have tended to grow in a spiral pattern, to be bisexual (in plants, this means both male and female parts on the same flower), and to be dominated by the
ovaryIn the flowering plants, an ovary is a part of the female reproductive organ of the flower or gynoecium. Specifically, it is the part of the carpel which holds the ovule and is located above or below or at the point of connection with the base of the petals and sepals...
(female part). As flowers grew more advanced, some variations developed parts fused together, with a much more specific number and design, and with either specific sexes per flower or plant, or at least "ovary inferior".
Flower evolution continues to the present day; modern flowers have been so profoundly influenced by humans that some of them cannot be pollinated in nature. Many modern, domesticated flowers used to be simple weeds, which only sprouted when the ground was disturbed. Some of them tended to grow with human crops, perhaps already having symbiotic companion plant relationships with them, and the prettiest did not get plucked because of their beauty, developing a dependence upon and special adaptation to human affection.
Classification
|
|
| The current phylogeny In biology, phylogenetics is the study of evolutionary relatedness among various groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...
of the flowering plants. |
There are eight groups of living angiosperms:
- Amborella
Amborella trichopoda is a rare, vesselless, understory shrub or small tree found only on the island of New Caledonia. It is of great interest in flora taxonomy because modern molecular phylogenetics data place it at or near the base of the flowering plants...
— a single species of shrub from New CaledoniaNew Caledonia , is a "sui generis collectivity" of France located in the region of Melanesia in the southwest Pacific. It comprises a main island , the Loyalty Islands, and several smaller islands...
- Nymphaeales
Nymphaeales is a botanical name at the rank of order. When recognized, it includes water lilies and sometimes other aquatic plants. This order is not part of the APG II system's 2003 plant classification , which instead has a broadly circumscribed family Nymphaeaceae unplaced in any order...
— about 80 species — water liliesNymphaeaceae is a name for a family of flowering plants. Members of this family are commonly called water lilies and live in freshwater areas in temperate and tropical climates around the world. The family contains 8 genera. There are about 70 species of water lilies around the world. The genus...
and HydatellaceaeHydatellaceae is a small family of flowering plants containing the genus Trithuria, which has been recently re-classified to include the genus Hydatella. The family consists of about a dozen species. These tiny , relatively simple, aquatic plants occur in Australasia and India. The simple leaves...
- Austrobaileyales
Austrobaileyales is the botanical name for an order of flowering plants, consisting of about 100 species of woody plants, perhaps the most famous of which is the spice star anise.- In different classifications :...
— about 100 species of woody plantA woody plant is a plant that uses wood as a structural tissue. They are typically perennial plants that have their stems and larger roots reinforced with wood produced adjacent to the vascular tissues: typically the main stem and larger branches and roots are covered by a layer of thickened bark....
s from various parts of the world
- Chloranthales — several dozen species of aromatic plants with toothed leaves
- Ceratophyllum
Ceratophyllum is a cosmopolitan genus of flowering plants, commonly found in ponds, marshes, and quiet streams in tropical and in temperate regions...
— about 6 species of aquatic plantAquatic plants — also called hydrophytic plants or hydrophytes — are plants that have adapted to living in or on aquatic environments. Because living on or under water surface requires numerous special adaptations, aquatic plants can only grow in water or permanently saturated soil...
s, perhaps most familiar as aquariumAn aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
plants
- magnoliids — about 9,000 species, characterized by trimerous
Merosity is the number of component parts in each whorls of a plant structure. It is most commonly used in the context of flowers, in which case it refers to the number of sepals in the calyx, the number of petals in the corolla, and the number of stamens in each whorl of the androecium...
flowers, pollen with one pore, and usually branching-veined leaves — for example 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,...
s, bay laurelThe Bay Laurel , also known as True Laurel, Sweet Bay, Laurel Tree, Grecian Laurel, Laurel, or Bay Tree, is an aromatic evergreen tree or large shrub reaching 10–18 m tall, native to the Mediterranean region.-Growth:The leaves are 6–12 cm long and 2–4 cm broad, with a characteristic...
, and black pepperBlack pepper is a flowering vine in the family Piperaceae, cultivated for its fruit, which is usually dried and used as a spice and seasoning. The fruit, known as a peppercorn when dried, is a small drupe approximately five millimetres in diameter, dark red when fully mature, containing a single...
- eudicots
Eudicots and Eudicotyledons are terms introduced by Doyle & Hotton to refer to a group of flowering plants that had been called "tricolpates" or "non-Magnoliid dicots" by previous authors. The term means, literally, "true dicotyledons" as it contains the majority of plants that have been...
— about 175,000 species, characterized by 4- or 5- merousMerosity is the number of component parts in each whorls of a plant structure. It is most commonly used in the context of flowers, in which case it refers to the number of sepals in the calyx, the number of petals in the corolla, and the number of stamens in each whorl of the androecium...
flowers, pollen with three pores, and usually branching-veined leaves — for example sunflowerSunflowers are annual plants native to the Americas, that possess a large inflorescence .-Description :...
s, petuniaPetunia is a trumpet shaped, widely-cultivated genus of flowering plants of South American origin, in the family Solanaceae. The popular flower derived its name from French, which took the word petun 'tobacco' from a Tupi-Guarani language. Most of the varieties seen in gardens are hybrids...
, buttercup, appleThe apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family Rosaceae. It is one of the most widely cultivated tree fruits...
s and 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...
s
- monocots — about 70,000 species, characterized by trimerous flowers, a single cotyledon
A cotyledon is a significant part of the embryo within the seed of a plant. Upon germination, the cotyledon may become the embryonic first leaves of a seedling. The number of cotyledons present is one characteristic used by botanists to classify the flowering plants...
, pollen with one pore, and usually parallel-veined leaves — for example grassPoaceae or Gramineae is a family in the Class Liliopsida of the flowering plants. Plants of this family are usually called grasses, or, to distinguish them from other graminoids, true grasses; the shrub- or tree-like plants in this family are called bamboo...
es, orchids, and palmArecaceae or Palmae , the palm family, is a family of flowering plants, the only family in the monocot order Arecales...
s
The exact relationship between these eight groups is not yet clear, although it has been determined that the first three groups to diverge from the ancestral angiosperm were Amborellales,
NymphaealesNymphaeales is a botanical name at the rank of order. When recognized, it includes water lilies and sometimes other aquatic plants. This order is not part of the APG II system's 2003 plant classification , which instead has a broadly circumscribed family Nymphaeaceae unplaced in any order...
, and
AustrobaileyalesAustrobaileyales is the botanical name for an order of flowering plants, consisting of about 100 species of woody plants, perhaps the most famous of which is the spice star anise.- In different classifications :...
.
History of classification
The botanical term "Angiosperm", from the
Ancient GreekAncient Greek is the historical stage in the development of the Greek language spanning across the Archaic , Classical , and Hellenistic periods of ancient Greece and the ancient world. It is predated in the 2nd millennium BC by Mycenaean Greek...
αγγείον,
angeíon (receptacle, vessel) and σπέρμα, (seed), was coined in the form Angiospermae by
Paul HermannPaul Hermann was a German born physician and botanist who for 15 years was director of the Hortus Botanicus Leiden....
in 1690, as the name of that one of his primary divisions of the plant
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...
. This included flowering plants possessing seeds enclosed in capsules, distinguished from his Gymnospermae, or flowering plants with
achenialAn achene is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate and indehiscent . Achenes contain a single seed that nearly fills the pericarp, but does not adhere to it...
or schizo-carpic fruits, the whole fruit or each of its pieces being here regarded as a seed and naked. The term and its antonym were maintained by
Carolus LinnaeusCarl Linnaeus was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature...
with the same sense, but with restricted application, in the names of the orders of his class Didynamia. Its use with any approach to its modern scope only became possible after 1827, when
Robert BrownRobert Brown FRS was a Scottish botanist who made important contributions to botany largely through his pioneering use of the microscope...
established the existence of truly naked ovules in the Cycadeae and
ConiferaeThe 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...
, and applied to them the name Gymnosperms. From that time onwards, so long as these Gymnosperms were, as was usual, reckoned as dicotyledonous flowering plants, the term Angiosperm was used antithetically by botanical writers, with varying scope, as a group-name for other dicotyledonous plants.
In 1851, Hofmeister discovered the changes occurring in the embryo-sac of flowering plants, and determined the correct relationships of these to the
CryptogamiaVascular 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...
. This fixed the position of Gymnosperms as a class distinct from Dicotyledons, and the term Angiosperm then gradually came to be accepted as the suitable designation for the whole of the flowering plants other than Gymnosperms, including the classes of Dicotyledons and Monocotyledons. This is the sense in which the term is used today.
In most taxonomies, the flowering plants are treated as a coherent group. The most popular descriptive name has been Angiospermae (Angiosperms), with Anthophyta ("flowering plants") a second choice. These names are not linked to any rank. The
Wettstein systemA system of plant taxonomy, the Wettstein system recognised the following main groups, according to* I. phylum Schizophyta*::: 1. classis Schizophyceae*::: 2. classis Schizomycetes* II. phylum Monadophyta* III. phylum Myxophyta...
and the
Engler systemOne of the prime systems of plant taxonomy, the Engler system was devised by Adolf Engler.According to Engler, Syllabus der Pflanzenfamilien the main groups of plants are:* I. divisio Schizophyta* II. divisio Phytosarcodina...
use the name Angiospermae, at the assigned rank of subdivision. The
Reveal systemA modern system of plant taxonomy, the Reveal system of plant classification was drawn up by the botanist J.L. Reveal , professor emeritus at the Norton Brown Herbarium, Maryland .The last update of the system was made in 1999...
treated flowering plants as subdivision Magnoliophytina (Frohne & U. Jensen ex Reveal, Phytologia 79: 70 1996), but later split it to Magnoliopsida, Liliopsida and Rosopsida. The
Takhtajan systemA system of plant taxonomy, the Takhtajan system of plant classification was published by Armen Takhtajan, in several versions from the 1950's onwards. It is usually compared to the Cronquist system. Key publications:External links:...
and
Cronquist systemA system of plant taxonomy, the Cronquist system is a scheme for the classification of flowering plants . This system was developed by Arthur Cronquist in his texts An Integrated System of Classification of Flowering Plants and The Evolution and Classification of Flowering Plants .Cronquist's...
treat this group at the rank of division, leading to the name Magnoliophyta (from the family name Magnoliaceae). The
Dahlgren systemOne of the modern systems of plant taxonomy, the Dahlgren system was published by monocot specialist Rolf Dahlgren. His wife Gertrude carried on after his death.According to the extensive listing by Professor Reveal One of the modern systems of plant taxonomy, the Dahlgren system was published by...
and
Thorne system (1992)A modern system of plant taxonomy, the Thorne system of plant classification was drawn up by the botanist Robert F. Thorne . He replaced it in 2000 with a new system. These two systems were published in:...
treat this group at the rank of class, leading to the name Magnoliopsida. However, the
APG systemA modern system of plant taxonomy, the APG system of plant classification was published in 1998 by the Angiosperm Phylogeny Group. The system is unusual in being based, not on total evidence, but on the cladistic analysis of the DNA sequences of three genes, two chloroplast genes and one gene...
, of 1998, and the
APG II systemA modern system of plant taxonomy, the APG II system of plant classification was published in 2003 by the Angiosperm Phylogeny Group, APG, in*Angiosperm Phylogeny Group . An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II. Botanical...
, of 2003, do not treat it as a formal taxon but rather treat it as a clade without a formal
botanical nameA botanical name is a formal scientific name conforming to the International Code of Botanical Nomenclature and, if the plant is a cultigen, the additional cultivar and/or Group epithets must conform to the International Code of Nomenclature for Cultivated Plants...
and use the name angiosperms for this clade.
The internal classification of this group has undergone considerable revision. The
Cronquist systemA system of plant taxonomy, the Cronquist system is a scheme for the classification of flowering plants . This system was developed by Arthur Cronquist in his texts An Integrated System of Classification of Flowering Plants and The Evolution and Classification of Flowering Plants .Cronquist's...
, proposed by
Arthur CronquistArthur John Cronquist was a North American botanist and a specialist on Compositae. He is considered one of the most influential botanists of the 20th century, largely due to his formulation of the Cronquist system. Two plant genera in the aster family have been named in his honor...
in 1968 and published in its full form in 1981, is still widely used, but is no longer believed to accurately reflect phylogeny. A general consensus about how the flowering plants should be arranged has recently begun to emerge, through the work of the
Angiosperm Phylogeny GroupThe Angiosperm Phylogeny Group, or APG, refers to two international groups of systematic botanists who came together to try to establish a consensus view of the taxonomy of flowering plants that would reflect new knowledge in angiosperm relationships based upon molecular systematics studies...
, who published an influential reclassification of the angiosperms in 1998. An update incorporating more recent research was published as APG II in 2003.
Traditionally, the flowering plants are divided into two groups, which in the Cronquist system are called
Magnoliopsida (at the rank of class, formed from the family name
Magnoliacae) and
Liliopsida (at the rank of class, formed from the family name
LiliaceaeThe Liliaceae, or the lily family, is a family of monocotyledons in the order Liliales. Plants in this family have linear leaves, mostly with parallel veins but with several having net venation , and flower arranged in threes. Several have bulbs, while others have rhizomes...
). Other descriptive names allowed by Article 16 of the ICBN include
Dicotyledones or
Dicotyledoneae, and
Monocotyledones or
Monocotyledoneae, which have a long history of use. In English a member of either group may be called a
dicotyledonDicotyledons, or "dicots", is a name for a group of flowering plants whose seed typically has two embryonic leaves or cotyledons. There are around 199,350 species within this group...
(plural
dicotyledons) and
monocotyledonMonocotyledons or monocots are one of two major groups of flowering plants that are traditionally recognized, the other being dicotyledons or dicots. Monocot seedlings typically have one cotyledon , in contrast to the two cotyledons typical of dicots. Monocots have been recognized at various...
(plural
monocotyledons), or abbreviated, as
dicot (plural
dicots) and
monocot (plural
monocots). These names derive from the observation that the dicots most often have two
cotyledonA cotyledon is a significant part of the embryo within the seed of a plant. Upon germination, the cotyledon may become the embryonic first leaves of a seedling. The number of cotyledons present is one characteristic used by botanists to classify the flowering plants...
s, or embryonic leaves, within each seed. The monocots usually have only one, but the rule is not absolute either way. From a diagnostic point of view the number of cotyledons is neither a particularly handy nor reliable character.
Recent studies, as by the APG, show that the monocots form holophyletic or monophyletic group; 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...]
is given the name
monocots. However, the dicots are not (they are a paraphyletic group). Nevertheless, within the dicots a monophyletic group does exist, called the
eudicotsEudicots and Eudicotyledons are terms introduced by Doyle & Hotton to refer to a group of flowering plants that had been called "tricolpates" or "non-Magnoliid dicots" by previous authors. The term means, literally, "true dicotyledons" as it contains the majority of plants that have been...
or
tricolpates, and including most of the dicots. The name
tricolpates derives from a type 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...
found widely within this group. The name
eudicots is formed combining
dicot with the prefix
eu- (from Greek, for "well," or "good," botanically indicating "true"), as the eudicots share the characters traditionally attributed to the dicots, such as flowers with four or five parts (four or five
petalA petal is one member or part of the corolla of a flower. The corolla is the name for all of the petals of a flower; the inner perianth whorl, term used when this is not the same in appearance as the outermost whorl and is used to attract pollinators based on its bright color...
s, four or five
sepalA sepal is a part of the flower of angiosperms . Sepals in most flowers are green and lie under the more conspicuous petals. As a collective unit the sepals form a calyx, whereas the collection of petals is called the corolla...
s). Separating this group of eudicots from the rest of the (former) dicots leaves a remainder, which sometimes are called informally
palaeodicots (Greek prefix
"palaeo-" means "old"). As this remnant group is not monophyletic this is a term of convenience only.
Flowering plant diversity
The number of
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
of flowering plants is estimated to be in the range of 250,000 to 400,000.
The number of
familiesIn biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus...
in APG (1998) was 462. In APG II (2003) it is not settled; at maximum it is 457, but within this number there are 55 optional segregates, so that the minimum number of families in this system is 402.
The diversity of flowering plants is not evenly distributed. Nearly all species belong to the eudicot (75%), monocot (23%) and magnoliid (2%) clades. The remaining 5 clades contain a little over 250 species in total, i.e., less than 0.1% of flowering plant diversity, divided among 9 families.
The most diverse families of flowering plants, in their APG circumscriptions, in order of number of species, are:
In the list above (showing only the 10 largest families), the Orchidaceae, Poaceae, and Cyperaceae are monocot families; the others are eudicot families.
Vascular anatomy
The amount and
complexityIn general usage, complexity tends to be used to characterize something with many parts in intricate arrangement. The study of these complex linkages is the main goal of network theory and network science...
of tissue-formation in flowering plants exceeds that of Gymnosperms. The
vascular bundleA vascular bundle is a part of the transport system in vascular plants. The transport itself happens in vascular tissue, which exists in two forms: xylem and phloem. Both these tissues are present in a vascular bundle, which in addition will include supporting and protective tissues...
s of the stem are arranged such that the
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"...
form concentric rings.
In the Dicotyledons, the bundles in the very young stem are arranged in an open ring, separating a central pith from an outer cortex. In each bundle, separating the xylem and phloem, is a layer of
meristemA meristem is the tissue in all plants consisting of undifferentiated cells and found in zones of the plant where growth can take place....
or active formative tissue known as
cambiumIn botany this is a layer or layers of tissue, also known as lateral meristems, that are the source of cells for secondary growth. There are two types of cambium*Cork cambium*Vascular cambium-References:...
. By the formation of a layer of cambium between the bundles (interfascicular cambium) a complete ring is formed, and a regular periodical increase in thickness results from the development of xylem on the inside and phloem on the outside. The soft phloem becomes crushed, but the hard wood persists and forms the bulk of the stem and branches of the woody perennial. Owing to differences in the character of the elements produced at the beginning and end of the season, the wood is marked out in transverse section into concentric rings, one for each
seasonA season is a division of the year, marked by changes in weather.Seasons result from the yearly revolution of the Earth around the Sun and the tilt of the Earth's axis relative to the plane of revolution...
of growth, called annual rings.
Among the Monocotyledons, the bundles are more numerous in the young stem and are scattered through the ground tissue. They contain no cambium and once formed the stem increases in diameter only in exceptional cases.
Flowers
The characteristic feature of angiosperms is the flower. Flowers show remarkable variation in form and elaboration, and provide the most trustworthy external characteristics for establishing relationships among angiosperm species. The function of the flower is to ensure fertilization of the ovule and development of
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...
containing
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...
s. The floral apparatus may arise terminally on a shoot or from the axil of a leaf (where the
petioleIn botany, the petiole is the small stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly...
attaches to the stem). Occasionally, as in
violetsViola is a genus of flowering plants in the violet family Violaceae, with around 400–500 species distributed around the world. Most species are found in the temperate Northern Hemisphere, however viola species are also found in widely divergent areas such as Hawaii, Australasia, and the Andes in...
, a flower arises singly in the axil of an ordinary foliage-leaf. More typically, the flower-bearing portion of the plant is sharply distinguished from the foliage-bearing or vegetative portion, and forms a more or less elaborate branch-system called an
inflorescenceAn inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
.
The reproductive cells produced by flowers are of two kinds. Microspores, which will divide to become
pollen grainsPollen 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...
, are the "male" cells and are borne in the
stamenThe stamen is the male organ of a flower. Each stamen generally has a stalk called the filament , and, on top of the filament, an anther , and pollen sacs,...
s (or microsporophylls). The "female" cells called megaspores, which will divide to become the egg-cell (
megagametogenesisMegagametogenesis is the development of a megaspore into an embryo sac, which is the gametophyte - though a highly reduced one - stage in the life cycle of vascular plants.-Eudicots:...
), are contained in the
ovuleOvule literally means "small egg." In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: The integuments forming its outer layer, the nucellus , and the megaspore-derived female gametophyte in its center...
and enclosed in the carpel (or megasporophyll).
The flower may consist only of these parts, as in
willowWillows, sallows, and osiers form the genus Salix, around 400 species of deciduous trees and shrubs, found primarily on moist soils in cold and temperate regions of the Northern Hemisphere...
, where each flower comprises only a few stamens or two carpels. Usually other structures are present and serve to protect the sporophylls and to form an envelope attractive to pollinators. The individual members of these surrounding structures are known as
sepalA sepal is a part of the flower of angiosperms . Sepals in most flowers are green and lie under the more conspicuous petals. As a collective unit the sepals form a calyx, whereas the collection of petals is called the corolla...
s and
petalA petal is one member or part of the corolla of a flower. The corolla is the name for all of the petals of a flower; the inner perianth whorl, term used when this is not the same in appearance as the outermost whorl and is used to attract pollinators based on its bright color...
s (or
tepalTepals are elements of the perianth, or outer part of a flower, which include the petals or sepals. The term tepal is usually used when all segments of the perianth are of similar shape and color, or undifferentiated...
s in flowers such as
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,...
where sepals and petals are not distinguishable from each other). The outer series (calyx of sepals) is usually green and leaf-like, and functions to protect the rest of the flower, especially the bud. The inner series (corolla of petals) is generally white or brightly colored, and is more delicate in structure. It functions to attract
insectInsects are arthropods, having a hard exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae. They are the most diverse group of animals on the planet and include more than a million species that are already described. Insects represent more than half of all...
or
birdBirds are winged, bipedal, endothermic , vertebrate animals that lay eggs. There are around 10,000 living species, making them the most numerous tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Birds range in size from the Bee Hummingbird to the ...
pollinators. Attraction is effected by color, scent, and nectar, which may be secreted in some part of the flower. The characteristics that attract pollinators account for the popularity of flowers and flowering plants among humans.
While the majority of flowers are perfect or
hermaphroditeIn a biological context, a hermaphrodite is an animal or plant that has both male and female reproductive organs.Many taxonomic groups of animals , do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both partners can...
(having both male and female parts in the same flower structure), flowering plants have developed numerous morphological and physiological mechanisms to reduce or prevent self-fertilization. Heteromorphic flowers have short carpels and long stamens, or vice versa, so animal
pollinatorA pollinator is the biotic agent that moves pollen from the male anthers of a flower to the female stigma of a flower to accomplish fertilization or syngamy of the female gamete in the ovule of the flower by the male gamete from the pollen grain...
s cannot easily transfer pollen to the pistil (receptive part of the carpel). Homomorphic flowers may employ a biochemical (physiological) mechanism called
self-incompatibilitySelf-incompatibility is a general name for several genetic mechanisms in angiosperms, which prevent self-fertilization and thus encourage outcrossing...
to discriminate between self- and non-self pollen grains. In other species, the male and female parts are morphologically separated, developing on different flowers.
Fertilization and embryogenesis
Double fertilizationDouble fertilization is a complex fertilization mechanism that has evolved in flowering plants, known as angiosperms. This process involves the joining of a female gametophyte with two male gametes . It begins when a pollen grain adheres to the stigma of the carpel, the female reproductive...
refers to a process in which two
spermThe term sperm is derived from the Greek word sperma and refers to the male reproductive cells. In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell...
cells fertilize
cellsThe cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of an organism that is classified as living, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos...
in the ovary. This process begins when a
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...
grain adheres to the stigma of the pistil (female reproductive structure), germinates, and grows a long
pollen tubeThe pollen tube of most seed plants acts as a conduit to transport sperm cells from the pollen grain, either from the stigma to the ovules at the base of the pistil, or directly through ovule tissue in some gymnosperms...
. While this pollen tube is growing, a haploid generative cell travels down the tube behind the tube nucleus. The generative cell divides by mitosis to produce two haploid (
n) sperm cells. As the pollen tube grows, it makes its way from the stigma, down the style and into the ovary. Here the pollen tube reaches the micropyle of the ovule and digests its way into one of the synergids, releasing its contents (which include the sperm cells). The synergid that the cells were released into degenerates and one sperm makes its way to fertilize the egg cell, producing a diploid (2
n) zygote. The second sperm cell fuses with both central cell nuclei, producing a triploid (3
n) cell. As the zygote develops into an embryo, the triploid cell develops into the endosperm, which serves as the embryo's food supply. The ovary now will develop into fruit and the ovule will develop into seed.
Fruit and seed
As the development of embryo and endosperm proceeds within the embryo-sac, the sac wall enlarges and combines with the nucellus (which is likewise enlarging) and the integument to form the
seed-coat. The ovary wall develops to form the
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...
or pericarp, whose form is closely associated with the manner of distribution of the seed.
Frequently the influence of fertilization is felt beyond the
ovaryThe ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in females are homologous to testes in males, in that they are both gonads and endocrine glands.-Human anatomy:...
, and other parts of the flower take part in the formation of the fruit,
e.g. the floral receptacle in the
appleThe apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family Rosaceae. It is one of the most widely cultivated tree fruits...
,
strawberryFragaria is a genus of flowering plants in the rose family, Rosaceae, commonly known as strawberries for their edible fruits. There are more than 20 described species and many hybrids and cultivars. The most common strawberries grown commercially are cultivars of the Garden strawberry...
and others.
The character of the seed-coat bears a definite relation to that of the fruit. They protect the embryo and aid in dissemination; they may also directly promote germination. Among plants with indehiscent fruits, the fruit generally provides protection for the embryo and secures dissemination. In this case, the seed-coat is only slightly developed. If the fruit is
dehiscentDehiscence is the opening at maturity of a plant structure, such as a fruit, anther, or sporangium, to release its contents.-Anther dehiscence:...
and the seed is exposed, the seed-coat is generally well developed, and must discharge the functions otherwise executed by the fruit.
Economic importance
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...
is almost entirely dependent on angiosperms, either directly or indirectly through
livestockLivestock are one or more domesticated animals raised in an agricultural setting to produce commodities such as food or fiber, or labor...
feed. Of all the families plants, the
PoaceaePoaceae or Gramineae is a family in the Class Liliopsida of the flowering plants. Plants of this family are usually called grasses, or, to distinguish them from other graminoids, true grasses; the shrub- or tree-like plants in this family are called bamboo...
, or grass family, is by far the most important, providing the bulk of all feedstocks (
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...
, corn —
maizeMaize , is a herbaceous plant domesticated in Mesoamerica and subsequently spread throughout the American continents...
,
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...
,
barleyBarley is a cereal grain derived from the annual grass Hordeum vulgare. It serves as a major animal feed crop, with smaller amounts used for malting and in health food. It is used in soups, stews and barley bread in various countries, such as Scotland and in Africa...
,
ryeRye is a grass grown extensively as a grain and as a forage crop. It is a member of the wheat tribe and is closely related to barley and wheat. Rye grain is used for flour, rye bread, rye beer, some whiskies, some vodkas, and animal fodder...
,
oatThe common oat is a species of cereal grain grown for its seed, which is known by the same name . While oats are suitable for human consumption as oatmeal and rolled oats, one of the most common uses is as livestock feed. Oats make up a large part of the diet of horses and are regularly fed to...
s,
pearl milletPearl millet is the most widely grown type of millet. Grown in Africa and the Indian subcontinent since prehistoric times, it is generally accepted that pearl millet originated in Africa and was subsequently introduced into India. The earliest archaeological records in India date to 2000 BC, so...
, sugar cane,
sorghumSorghum is a genus of numerous species of grasses, some of which are raised for grain and many of which are used as fodder plants either cultivated or as part of pasture. The plants are cultivated in warmer climates worldwide. Species are native to tropical and subtropical regions of all continents...
). The
FabaceaeFabaceae or Leguminosae is a large and economically important family of flowering plants, which is commonly known as the legume family, pea family, bean family or pulse family. The name 'Fabaceae' comes from the defunct genus Faba, now included into Vicia...
, or legume family, comes in second place. Also of high importance are the
SolanaceaeThe Solanaceae is a family of flowering plants that contains a number of important agricultural plants as well as many toxic plants. The name of the family comes from the Latin Solanum "the nightshade plant", but the further etymology of that word is unclear...
, or nightshade family (
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...
es,
tomatoThe tomato is a herbaceous, usually sprawling plant in the Solanaceae or nightshade family that is typically cultivated for the purpose of harvesting its fruit for human consumption...
es, and
pepperCapsicum is a genus of plants from the nightshade family native to the Americas, where it was cultivated for thousands of years by the people of the tropical Americas, and is now cultivated worldwide. Some of the members of Capsicum are used as spices, vegetables, and medicines...
s, among others), the
CucurbitaceaeCucurbitaceae is a plant family commonly known as melons, gourds or cucurbits and includes crops like cucumbers, squashes , luffas, melons and watermelons...
, or
gourdA gourd is a plant of the family Cucurbitaceae, or a name given to the hollow, dried shell of a fruit in the Cucurbitaceae family of plants of the genus Lagenaria...
family (also including
pumpkinPumpkin is a gourd-like squash of the genus Cucurbita and the family Cucurbitaceae . It is a common name of or can refer to cultivars of any one of the species Cucurbita pepo, Cucurbita mixta, Cucurbita maxima, and Cucurbita moschata. They are typically orange or yellow and have many creases...
s and
melonMelon is a name given to various members of the Cucurbitaceae family with fleshy fruit. Melon can refer to either the plant or the fruit, which is a false berry. Many different cultivars have been produced, particularly of muskmelons...
s), the
BrassicaceaeBrassicaceae or Cruciferae, also known as the crucifers, the mustard family or cabbage family is a family of flowering plants . The name Brassicaceae is derived from the included genus Brassica. Cruciferae is an older name, meaning "cross-bearing", because the four petals of their flowers are...
, or
mustard plantMustards are several plant species in the genera Brassica and Sinapis whose small mustard seeds are used as a spice and, by grinding and mixing them with water, vinegar or other liquids, are turned into the condiment known as mustard...
family (including
rapeseedRapeseed , also known as rape, oilseed rape, rapa, rapaseed and canola, is a bright yellow flowering member of the family Brassicaceae...
and
cabbageThe cabbage is a popular cultivar of the species Brassica oleracea Linne of the Family Brassicaceae , and is used as a leafy green vegetable...
), and the
ApiaceaeThe Apiaceae or Umbelliferae is a family of usually aromatic plants with hollow stems, commonly known as umbellifers. It includes cumin, parsley, carrot, coriander/cilantro, dill, caraway, fennel, parsnip, celery, Queen Anne's Lace and other relatives. It is a large family with about 300 genera...
, or
parsleyParsley is a bright green biennial herb, often used as spice. It is common in Middle Eastern, European, and American cooking...
family. Many of our fruits come from the
RutaceaeRutaceae, commonly known as the rue or citrus family, is a family of plants, usually placed in the order Sapindales.Species of the family generally have flowers that divide into four or five parts, usually with strong scents...
, or rue family, and the
RosaceaeThe Rosaceae or rose family is a large family of plants, with about 3000 species in 100 genera . The name is derived from the genus Rosa...
, or rose family (including
appleThe apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family Rosaceae. It is one of the most widely cultivated tree fruits...
s,
pearThe pear is a tree of genus Pyrus and also the name of the tree's edible pomaceous fruit. The pear is classified within Maloideae, a subfamily within Rosaceae...
s,
cherriesThe cherry is the fruit of many plants of the genus Prunus. It is a fleshy fruit that contains a single stony seed. The cherry fruits of commerce are usually obtained from a limited number of species, including especially cultivars of the wild cherry, Prunus avium.The name 'cherry', often as the...
, apricots, plums, etc.).
In some parts of the world, certain single species assume paramount importance because of their variety of uses, for example the coconut (
Cocos nuciferaThe Coconut Palm is a member of the family Arecaceae . It is the only species in the genus Cocos, and is a large palm, growing to 30 m tall, with pinnate leaves 4–6 m long, pinnae 60–90 cm long; old leaves break away cleanly leaving the trunk smooth. The term coconut refers to the seed of the...
) on Pacific
atollAn atoll is an island of coral that encircles a lagoon partially or completely.- Usage :The word atoll comes from the Dhivehi word atholhu
OED. Its first recorded use in English was in 1625 as atollon...
s, and the olive (
Olea europaeaThe 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...
) in the Mediterranean region.
Flowering plants also provide economic resources in the form of
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...
,
paperPaper is thin material mainly used for writing upon, printing upon or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....
, fiber (
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...
, and
hempHemp is the name of the soft, durable fiber that is cultivated from plants of the Cannabis genus, cultivated only for industrial use....
, among others), medicines (
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...
,
camphorCamphor is a waxy, white or transparent solid with a strong, aromatic odor. It is a terpenoid with the chemical formula C
10H
16O. It is found in wood of the camphor laurel , a large evergreen tree found in Asia and also of Dryobalanops aromatica, a giant of the Bornean forests...
), decorative and landscaping plants, and many other uses. The main area in which they are surpassed by other plants is
timberTimber may refer to:*Lumber, i.e. wood materials* Timber, Oregon, an unincorporated community in the U.S. state of Oregon* Timber , a 1984 arcade game by Bally Midway* An alternative spelling for Timbre...
production.
External links
- Angiosperms — UC Berkeley video lecture
- Cronquist, Arthur. (1981) An Integrated System of Classification of Flowering Plants. Columbia Univ. Press, New York.
- Dilcher, D. 2000. Toward a new synthesis: Major evolutionary trends in the angiosperm fossil record. PNAS [Proceedings of the National Academy of Sciences of the United States of America] 97: 7030-7036 (available online here)
- Oldest Known Flowering Plants Identified By Genes, William J. Cromie, Harvard Gazette, December 16, 1999.
- L. Watson and M.J. Dallwitz (1992 onwards). The families of flowering plants: descriptions, illustrations, identification, information retrieval.
- Simpson, M.G. Plant Systematics. Elsevier Academic Press. 2006.
- Raven, P.H., R.F. Evert, S.E. Eichhorn. Biology of Plants, 7th Edition. W.H. Freeman. 2004.