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Seed

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	Topics Seed Topic Home A seed Seeds have been an important development in the reproduction and spread of flowering plants, relative to more primitive plants like mossMoss Mosses are small, soft plants that are typically 1-10 cm tall, occasionally more.... es, fernFern A fern is any one of a group of about 20,000 species of plants classified in the phylum or division Pteridophyta, also... s and liverworts, which do not have seeds and use other means to propagate themselves. This can be seen by the success of seed plants (both gymnosperms and angiosperms) in dominating biological nicheEcological niche In ecology, a niche is a term describing the relational position of a species or population in an ecosystem.... s on land, from forestForest A forest is an area with a high density of trees .... s to grasslandGrassland A grassland is a generally open and continuous, fairly flat area of grass.... s both in hot and cold climates. The term seed also has a general meaning that predates the above — anything that can be sownSowing Sowing is the process of planting seeds.... i.e. "seed" potatoPotato The potato is a perennial plant of the Solanaceae, or nightshade, family, commonly grown for its starchy tuber.... es, "seeds" of cornMaize Maize , also known as corn, is a cereal grain that was domesticated in Mesoamerica.... or sunflower "seeds"Sunflower seed The sunflower seed is the seed of the sunflower .... . In the case of sunflowerSunflower The sunflower is an annual plant in the family Asteraceae, with a large flower head .... and corn "seeds", what is sown is the seed enclosed in a shell or hull, and the potato is a tuber. Seed structure A typical seed includes three basic parts: (1) an embryoEmbryo An embryo is a multicellular diploid eukaryote in its earliest stage of development. ... , (2) a supply of nutrients for the embryo, and (3) a seed coat. The embryoEmbryo An embryo is a multicellular diploid eukaryote in its earliest stage of development. ... is an immature plantPlant Summary Plants are a major group of living things including familiar organisms such as trees, flowers, herbs, ferns, and mosses.... from which a new plant will grow under proper conditions. The embryo has one cotyledonCotyledon Overview A cotyledon is a significant part of the embryo within the seed of a plant.... or seed leaf in monocotyledonMonocotyledon Insert non-formatted text hereThe Monocotyledons or monocots are a group of flowering plants, dominating great parts ... s, two cotyledons in almost all dicotyledonDicotyledon Dicotyledons or "dicots" is a name for a group of flowering plants whose seed typically contains two embryonic leaves ... s and two or more in gymnosperms. The radicleRadicle In botany, the radicle is the first part of a seedling to emerge from the seed during the process of germination.... is the embryonic root. The plumule is the embryonic shoot. The embryonic stem above the point of attachment of the cotyledon(s) is the epicotylEpicotyl In plant physiology, the epicotyl is the embryonic shoot above the cotyledons.... . The embryonic stem below the point of attachment is the hypocotylHypocotyl Hypocotyl is a botanical term for a part of a germinating seedling of a seed plant.... . Within the seed, there usually is a store of nutrientNutrient Summary A nutrient is any element or compound necessary for or contributing to an organism's metabolism, growth, or other functionin... s for the seedlingSeedling A seedling is a young plant sporophyte developing out of a plant embryo from a seed.... that will grow from the embryo. The form of the stored nutrition varies depending on the kind of plant. In angiosperms, the stored food begins as a tissue called the endospermEndosperm Endosperm is a usually triploid tissue produced in the seeds of most flowering plants.... , which is derived from the parent plant via double fertilization. The usually triploid endosperm is rich in oil or starchStarch Starch is a complex carbohydrate which is insoluble in water; it is used by plants as a way to store excess glucose.... and proteinProtein Proteins are large organic compounds made of amino acids arranged in a linear chain and joined by peptide bonds.... . In gymnosperms, such as coniferPinophyta The conifers, division Pinophyta, also known as division Coniferae, are one of 13 or 14 division level taxa with... s, the food storage tissue is part of the female gametophyte, a haploid tissue. In some species, the embryo is embedded in the endosperm or female gametophyte, which the seedling will use upon germinationGermination Germination is the process where growth emerges from a resting stage.... . In others, the endosperm is absorbed by the embryo as the latter grows within the developing seed, and the cotyledons of the embryo become filled with this stored food. At maturity, seeds of these species have no endosperm and are termed exalbuminous seeds. Some exalbuminous seeds are beanBean Bean is a common name for large plant seeds of several genera of Fabaceae used for food or feed.... , peaPea A pea is the small, edible round green bean which grows in a pod on the leguminous vine *Pisum sativum, or in some ... , oakOak Overview The term oak* can be used as part of the common name of any of several hundred species of trees and shrubs in the genus Que... , walnutWalnut The walnuts are plants in the walnut family Juglandaceae.... , squash, sunflowerSunflower The sunflower is an annual plant in the family Asteraceae, with a large flower head .... , and radishRadish The radish is a root vegetable of the Brassicaceae family.... . Seeds with an endosperm at maturity are termed albuminous seeds. Most monocots (e.g. grassesFacts About Poaceae The true grasses are monocotyledonous plants in the Family Poaceae, also known as Gramineae.... and palmsArecaceae Arecaceae , the Palm Family, is a family of flowering plants belonging to the monocot order, Arecales.... ) and many dicots (e.g. brazil nutBrazil Nut The Brazil Nut is a South American tree Bertholletia excelsa in the family Lecythidaceae.... and castor bean) have albuminous seeds. All gymnosperm seeds are albuminous. The seed coat (or testa) develops from the tissue, the integument, originally surrounding the ovule. The seed coat in the mature seed can be a paper-thin layer (e.g. peanutPeanut The peanut or groundnut is a species in the legume family Fabaceae native to South America.... ) or something more substantial (e.g. thick and hard in honey locustHoney locust The Honey locust is a deciduous tree native to eastern North America.... and coconutCoconut The Coconut Palm , is a member of the Family Arecaceae .... ). The seed coat helps protect the embryo from mechanical injury and from drying out. In addition to the three basic seed parts, some seeds have an appendage on the seed coat such an arilAril An aril is a fleshy covering of certain seeds formed from the *funiculus.... (as in yewTaxus Taxus* is a genus of yews, small coniferous trees or shrubs in the yew family Taxaceae.... and nutmegNutmeg The nutmegs *Myristica* are a genus of evergreen trees indigenous to tropical southeast Asia and Australasia.... ) or an elaiosomeElaiosome Summary Elaiosomes are fleshy structures that are attached to the seeds of many plant species.... (as in CorydalisCorydalis *Corydalis* is a genus of about 300 species of annual and perennial herbaceous flowering plants in the family Fumariaceae,... ) or hairs (as in cottonCotton Cotton is a soft fiber that grows around the seeds of the cotton plant , a shrub native to the tropical and subtropical regi... ). There may also be a scar on the seed coat, called the hilum; it is where the seed was attached to the ovary wall by the funiculusOvule Overview An ovule is a structure found in seed plants that develops into a seed after fertilization.... . Seed production Seeds are produced in several related groups of plants, and their manner of production distinguishes the angiosperms ("enclosed seeds") from the gymnospermGymnosperm Gymnosperms are a group of seed-bearing plants which bear seeds on cone-like structures rather than inside fruit like angios... s ("naked seeds"). Angiosperm seeds are produced in a hard or fleshy (or with layers of both) structure called a fruitFruit The term fruit has different meanings depending on context.... that encloses the seeds, hence the name. In gymnosperms, no special structure develops to enclose the seeds, which begin their development "naked" on the bracts of cones. However, the seeds do become covered by the coneConifer cone A cone is an organ on plants in the division Pinophyta that contains the reproductive structures.... scales as they develop in some species of conifer. Kinds of seeds There are a number of modifications to seeds by different groups of plants. One example is that of the so-called stoneDrupe In botany, a drupe is a type of fruit in which an outer fleshy part surrounds a shell of hardened endocarp with a seed ins... fruits (such as the peachPeach The Peach is a tree native to China that bears a juicy fruit of the same name.... ), where a hardened fruit layer ( the endocarp) surrounds the actual seed and is fused to it. Many structures commonly referred to as "seeds" are actually dry fruitFruit The term fruit has different meanings depending on context.... s. SunflowerSunflower The sunflower is an annual plant in the family Asteraceae, with a large flower head .... seeds are sold commercially while still enclosed within the hard wall of the fruit, which must be split open to reach the seed. Seed development The seed, which is an embryo with two points of growth (one of which forms the stems the other the roots) is enclosed in a seed coat with some food reserves. Angiosperm seeds consist of three genetically distinct constituents: (1) the embryo formed from the zygote, (2) the endosperm, which is normally triploid, (3) the seed coat from tissue derived from the maternal tissue of the ovule. In angiosperms, the process of seed development begins with double fertilization and involves the fusion of the egg and sperm nuclei into a zygote. The second part of this process is the fusion of the polar nuclei with a second sperm cell nucleus, thus forming a primary endospermEndosperm Endosperm is a usually triploid tissue produced in the seeds of most flowering plants.... . Right after fertilization the zygote is mostly inactive but the primary endosperm divides rapidly to form the endosperm tissue. This tissue becomes the food that the young plant will consume until the roots have developed after germination or it develops into a hard seed coat. The seed coat forms from the two integuments or outer layers of cells of the ovule, which derive from tissue from the mother plant, the inner integument forms the tegmenTegmen A tegmen designates the modified leathery front wing on an insect.... and the outer forms the testa. When the seed coat forms from only one layer it is also called the testa, though not all such testa are homologous from one species to the next. In gymnosperms, the two sperm cells transferred from the pollen do not develop seed by double fertilization but instead only one sperm fertilizes the egg while the other is not used. The seed is composed of the embryo (the result of fertilization) and tissue from the mother plant, which also form a cone around the seed in coniferous plants like PinePine Pines are coniferous trees of the genus *Pinus, in the family Pinaceae.... and SpruceSpruce Spruce* refers to trees of the Genus *Picea, a genus of about 35 species of coniferous evergreen trees in the Family... . The ovules after fertilization develop into the seeds; the main parts of the ovule are the funicle; which attaches the ovule to the placenta, the nucellus; the main region of the ovule were the embryo sac develops, the micropyle; A small pore or opening in the ovule where the pollen tube usually enters during the process of fertilization, and the chalazaChalaza Summary Chalaza* is a Greek word - from khalaze - meaning "hailstone".... ; the base of the ovule opposite the micropyle, where integument and nucellus are joined together. The shape of the ovules as they develop often affects the finale shape of the seeds. Plants generally produce ovules of four shapes: the most common shape is called anatropous, with a curved shape. Orthotropous ovules are straight with all the parts of the ovule lined up in a long row producing an uncurved seed. Campylotropous ovules have a curved embryo sac often giving the seed a tight “c” shape. The last ovule shape is called amphitropous, where the ovule is partly inverted and turned back 90 degrees on its stalk or funicle. In the majority of flowering plants the zygotes first division is transversely orientated in regards to the long axis and this establishes the polarity of the embryo. The upper or chalazal pole becomes the main area of growth of the embryo, while the lower or micropylar pole produces the stalk-like suspensor that attaches to the micropyle. The suspensor absorbs and manufacturers nutrients from the endosperm that are utilized during the embryos growth. The embryo is composed of different parts; the epicotyle will grow into the shoot, the radicle grows into the primary root, the hypocotyl connects the epicotyle and the radicle, the cotyledons form the seed leaves, the testa or seed coat forms the outer covering of the seed. Monocotyledonous plants like corn, have other structures; instead of the hypocotyle-epicotyle, it has a coleoptile that forms the first leaf and connects to the coleorhiza that connects to the primary root and adventitiousAdventitious Adventitious, in botany, refers to structures that develop in an unusual place, and in medicine, it refers to conditions acq... roots form from the sides. The seeds of corn are constructed with these structures; pericarp, scutellum (single large cotyledon) that absorbs nutrients from the endosperm, endosperm, plumule, radicle, coleoptile and coleorhiza - these last two structures are sheath-like and enclose the plumule and radicle, acting as a protective covering. The testa or seed coats of both monocots and dicots are often marked with patterns and textured markings, or have wings or tufts of hair. Seed size and seed set Seeds are very diverse in size. The dust-like orchid seeds are the smallest with about one million seeds per gram, they are often embryonic seeds with immature embryos and no significant energy reserves. Orchids and a few other groups of plants are myco-heterotrophsMyco-heterotrophy Myco-heterotrophy is a symbiotic relationship between certain kinds of plants and fungi, in which the plant gets all or part... which depend on mycorrhizal fungiMycorrhizal fungi Mycorrhizal fungi refer to species of fungi that form a symbiotic relationship with plants, exchanging nutrients at fungal/r... for nutrition during germination and the early growth of the seedling. Some terrestrial Orchid seedlings, in fact, spend the first few years of their life deriving energy from the fungus and do not produce green leaves. At over 20 kg, the largest seed is the coco de merCoco de mer The Coco de mer, the sole member of the genus Lodoicea, is a palm endemic to the islands of Praslin and Curieuse in the ... . Plants that produce smaller seeds can generate many more seeds per flower, while plants with larger seeds invest more resources into those seeds and normally produce fewer seeds. Small seeds are quicker to ripen and can be dispersed sooner, so fall blooming plants often have small seeds. Many annual plants produce great quantities of smaller seeds; this helps to ensure that at least a few will end in a favorable place for growth. Herbaceous perennials and woody plants often have larger seeds, they can produce seeds over many years, and larger seeds have more energy reserves for germination and seedling growth and produce larger, more established seedlings after germination. Seed functions Seeds serve several functions for the plants that produce them. Key among these functions are nourishment of the embryoEmbryo Overview An embryo is a multicellular diploid eukaryote in its earliest stage of development. ... , dispersalBiological dispersal Biological dispersal refers to those processes by which a species maintains or expands the distribution of a population.... to a new location, and dormancyDormancy Dormancy is a period in an organism's life cycle when development is temporarily suspended.... during unfavorable conditions. Seeds fundamentally are a means of reproduction and most seeds are the product of sexual reproductionSexual reproduction Sexual reproduction is a type of reproduction that results in increasing genetic diversity of the offspring.... which produces a remixing of genetic material and phenotypePhenotype The phenotype of an individual organism is either its total physical appearance and constitution or a specific manifestation... variability that natural selectionNatural selection Natural selection is the process by which individual organisms with favorable traits are more likely to survive and reproduc... acts on. Embryo nourishment Seeds protect and nourish the embryo or baby plant. Seeds usually give a seedling a faster start than a sporling from a spore gets because of the larger food reserves in the seed. Seed dispersal Unlike animals, plants are limited in their ability to seek out favorable conditions for life and growth. As a consequence, plants have evolved many ways to disperseBiological dispersal Biological dispersal refers to those processes by which a species maintains or expands the distribution of a population.... their offspring by dispersing their seeds (see also vegetative reproductionVegetative reproduction Vegetative reproduction is a type of asexual reproduction found in plants also called vegetative propagation or veg... ). A seed must somehow "arrive" at a location and be there at a time favorable for germination and growth. When the fruits open and release their seeds in a regular way, it is called dehiscent, which is often distinctive for related groups of plants, these fruits include; Capsules, follicles, legumes, silicles and siliques. When fruits do not open and release their seeds in a regular fashion they are called indehiscent, which include these fruits; Achenes, caryopsis, nuts, samaras, and utricles. Seed dispersal is seen most obviously in fruits; however many seeds aid in their own dispersal. Some kinds of seeds are dispersed while still inside a fruitFruit The term fruit has different meanings depending on context.... or coneConifer cone A cone is an organ on plants in the division Pinophyta that contains the reproductive structures.... , which later opens or disintegrates to release the seeds. Other seeds are expelled or released from the fruit prior to dispersal. For example, milkweeds produce a fruit type, known as a follicleFollicle (fruit) In botany, a follicle is a dry unilocular many-seeded fruit formed from one carpel and dehiscing by the ventral suture in or... , that splits open along one side to release the seeds. IrisFacts About Iris (plant) *Iris* is a genus of between 200-300 species of flowering plants with showy flowers which takes its name from the Greek wo... capsulesCapsule (fruit) In botany a capsule is a type of simple, dry fruit produced by many species of flowering plants.... split into three "valves" to release their seeds. By wind Many seeds (e.g. mapleMaple Maples are trees or shrubs of the genus Acer.... , pinePine Pines are coniferous trees of the genus *Pinus, in the family Pinaceae.... ) have a wing that aids in wind dispersal. The dustlike seeds of orchids are carried efficiently by the wind. Some seeds, (e.g. dandelionDandelion Dandelion* is a large genus of flowering plants in the \|family]] Asteraceae.... , milkweed, poplarPoplar *Populus* is a genus of trees which includes the cottonwoods, poplars, and aspens, all of which are sometimes termed po... ) have hairs that aid in wind dispersal. By water Some plants, such as MucunaMucuna *Mucuna* is a genus of 33 accepted species of climbing vines and shrubs of the family\|family Fabaceae, found worldwide in... and DiocleaDioclea The genus Dioclea is a member of the family Fabaceae native to the Americas.... , produce buoyant seeds termed sea-beans or drift seeds because they float in rivers to the oceans and wash up on beaches. By animals Seeds\|burr]]s) with barbs or hooks (e.g. acaenaAcaena *Acaena* is a genus of about 100 species of perennial herbs and subshrubs in the Rosaceae, native mainly to the Southern H... , burdockBurdock Burdock is any of a group of biennial thistles in the genus *Arctium, family Asteraceae.... , dockRumex The docks* and sorrels, genus *Rumex* L., are a genus of about 200 species of annual, biennial and perennial he... which attach to animal fur or feathers, and then drop off later. Seeds with a fleshy covering (e.g. appleApple The apple is a tree and its pomaceous fruit, of the species Malus domestica in the rose family Rosaceae.... , cherryCherry A cherry is both a tree and its fleshy fruit, a type known as a drupe with a single hard stone enclosing the seed.... , juniperJuniper Junipers are coniferous plants in the genus *Juniperus* of the cypress family Cupressaceae.... ) are eaten by animals which then disperse these seeds in their droppings. Seeds\|nuts]]) which are an attractive long-term storable food resource for animals (e.g. acornAcorn The acorn is the fruit of the oak tree.... s, hazelHazel The hazels are a genus of about ten species of deciduous trees and large shrubs native to the temperate northern hemisphere.... nut, walnutWalnut The walnuts are plants in the walnut family Juglandaceae.... ); the seeds are stored some distance from the parent plant, and some escape being eaten if the animal forgets them. MyrmecochoryMyrmecochory Myrmecochory is a botanical term for "seed dispersal by ants".... is the dispersal of seeds by antAnt Ants are one of the most successful groups of insects in the animal kingdom.... s. Foraging ants disperse seeds which have appendages called elaiosomeElaiosome Elaiosomes are fleshy structures that are attached to the seeds of many plant species.... s (e.g. bloodrootBloodroot *Bloodroot* is a perennial, herbaceous flowering plant native to eastern North America from Nova Scotia, Canada southward ... , trilliumTrillium *Trillium* is a genus of about 40-50 species of perennial herbaceous flowering plants, native to temperate regions of Nort... s, AcaciaAcacia *Acacia* is a genus of shrubs and trees of Gondwanian origin belonging to the Subfamily Mimosoideae of the Pea Family , fi... s, and many species of ProteaceaeProteaceae *Proteaceae* is a family of flowering plants.... ). Elaiosomes are soft, fleshy structures that contain nutrients for animals that eat them. The ants carry such seeds back to their nest, where the elaiosomes are eaten. The remainder of the seed, which is hard and inedible to the ants, then germinates either within the nest or at a removal site where the seed has been discarded by the ants. This dispersal relationship is an example of mutualismMutualism In biology, mutualism is an interaction between two or more species where both species derive benefit.... , since the plants depend upon the ants to disperse seeds, while the ants depend upon the plants seeds for food. As a result, a drop in numbers of one partner can reduce success of the other. In South AfricaSouth Africa The Republic of South Africa is a country located at the southern tip of the African continent.... , the Argentine antArgentine ant Native to northern Argentina and parts of Uruguay, Paraguay and Brazil, the Argentine ant has spread to many areas around th... (Linepithema humile) has invadedInvasive species The term invasive species refers to a subset of those species defined as introduced species or non-indigenous species.... and displaced native species of ants. Unlike the native ant species, Argentine ants do not collect the seeds of Mimetes cucullatus or eat the elaiosomes. In areas where these ants have invaded, the numbers of Mimetes seedlingSeedling A seedling is a young plant sporophyte developing out of a plant embryo from a seed.... s have dropped. Seed dormancy and protection One important function of most seeds is delaying germination, which allows time for dispersal and prevents germination of all the seeds at one time. The staggering of germination safeguards some seeds and seedlings from suffering damage or death from short periods of bad weather or from transient herbivores, it also allows some to germinate when competition from other plants for light and water might be less. Many species of plants have seeds that germinate over many months or years, and some seeds can remain in the soil seed bank for more than 50 years before germination. Some seed have a very long viability period, with the oldest documented germinating seed carbon dated to be 2000 years old. Seed dormancy is defined as a seed failing to germinate under environmental conditions optimal for germination, normally when the environment is at a suitable temperature with proper soil moisture. Induced dormancy or seed quiescence occurs when a seed fails to germinate because the external environmental conditions are inappropriate for germination, mostly in response to being too cold or hot, or too dry. True dormancy or innate dormancy is caused by conditions within the seed that prevent germination under normally ideal conditions. Often seed dormancy is divided into four major categories: exogenous; endogenous; combinational; and secondary. Exogenous dormancy is caused by conditions outside the embryo including: Hard seed coats or physical dormancy occurs when seeds are impermeablePermeability (fluid) In the earth sciences, permeability is a measure of the ability of a material to transmit fluids.... to water or the exchange of gases. In some seeds the seed coat physically prevents the seedling from growing. Chemical dormancy includes growth regulators etc. Endogenous dormancy is caused by conditions within the embryo itself, including: Immature embryos where some plants release their seeds before the tissues of the embryos have fully differentiated, and the seeds ripen after they take in water while on the ground, germination can be delayed from a few weeks to a few months. Morphological dormancy where seeds have fully differentiated embryos that need to grow more before seed germination, the embryos are not yet fully developed. Morphophysiological dormancy seeds with underdeveloped embryos, and in addition have physiological components to dormancy. These seeds therefore require a dormancy-breaking treatments as well as a period of time to develop fully grown embryos. Physiological dormancy prevents seed germination until the chemical inhibitors are broken down or are no longer produced by the seed, often physiological dormancy is broken by a period of cool moist conditions, normally below (+4C) 39F, or in the case of many species in RanunculaceaeRanunculaceae Ranunculaceae is a family of flowering plants.... and a few others,(-5C) 24F. Other chemicals that prevent germination are washed out of the seeds by rainwater or snow melt. Abscisic acidAbscisic acid Abscisic Acid, also known as abscisin II, is a plant hormone.... is usually the growth inhibitor in seeds and its production can be affected by light. Some plants like PeonyPeony The peony or paeony is the sole genus in the flowering plant family Paeoniaceae.... species have multiple types of physiological dormancy, one affects radical growth while the other affects shoot growth. Drying; some plants including a number of grasses and those from seasonally arid regions need a period of drying before they will germinate, the seeds are released but need to have a lower moister content before germination can begin. If the seeds remain moist after dispersal, germination can be delayed for many months or even years. Many herbaceous plants from temperate climate zones have physiological dormancy that disappears with drying of the seeds. Other species will germinate after dispersal only under very narrow temperature ranges, but as the seeds dry they are able to germinate over a wider temperature range. Photodormancy or light sensitivity affects germination of some seeds. These photoblastic seeds need a period of darkness or light to germinate. In species with thin seed coats, lightLight Light is electromagnetic radiation with a wavelength that is visible to the eye or, in a technical or scientific context, e... may be able to penetrate into the dormant embryo. The presence of light or the absence of light may trigger the germination process, inhibiting germination in some seeds buried too deeply or in others not buried in the soil. Thermodormancy is seed sensitivity to heat or cold. Some seeds including cocklebur and amaranth germinate only at high temperatures (30C or 86F) many plants that have seed that germinate in early to mid summer have thermodormancy and germinate only when the soil temperature is warm. Other seeds need cool soils to germinate, while others like celery are inhibited when soil temperatures are too warm. Often thermodormancy requirements disappear as the seed ages or dries. Combinational dormancy also called double dormancy. Many seeds have more than one type of dormancy, some IrisIris (plant) Summary *Iris* is a genus of between 200-300 species of flowering plants with showy flowers which takes its name from the Greek wo... species have both hard impermeable seeds coats and physiological dormancy. Secondary dormancy is caused by conditions after the seed has been dispersed and occurs in some seeds when non-dormant seed is exposed to conditions that are not favorable to germination, very often high temperatures. The mechanisms of secondary dormancy are not yet fully understood but might involve the loss of sensitivity in receptors in the plasma membrane. Many garden plants have seeds that will germinate readily as soon as they have water and are warm enough, though their wild ancestors may have had dormancy, these cultivated plants lack seed dormancy. After many generations of selective pressure by plant breeders and gardeners dormancy has been selected out. For annualsAnnual plant Botanically, an annual plant is a plant that usually germinates, flowers and dies in one year.... , seeds are a way for the species to survive dry or cold seasons. Ephemeral plants are usually annuals that can go from seed to seed in as few as six weeks. Not all seeds undergo a period of dormancy. Seeds of some mangroveMangrove Mangroves are woody trees or shrubs that grow in coastal habitats or mangal, for which the term mangrove swamp'... s are viviparous, they begin to germinate while still attached to the parent. The large, heavy root allows the seed to penetrate into the ground when it falls. Seed germination Seed germination is the process of growth of the embryo into a functional plant. It involves the reactivation of the metabolic pathways that lead to growth and the emergence of the radicle or seed root and plumule or shoot. Three fundamental conditions must exist before germination can occur. (1) The embryo must be alive, called seed viability. (2) Any dormancy requirements that prevent germination must be over come. (3) The proper environmental conditions must exist for germination. Seed viability determines the percentage of possible seed germination and is affected by a number of different conditions. Some plants do not produce seeds that have functional complete embryos or the seed may have no embryo at all, often called empty seeds. Predators and pathogens can damage or kill the seed while it is still in the fruit or after it is dispersed. Environmental conditions like flooding or heat can kill the seed before or during germination. The age of the seed affects its health and germination ability, since the seed has a living embryo, over time cells die and cannot be replaced. Some seeds can live for a long time before germination, while others can only survive for a short period after dispersal before they die. Seed vigor is a measure of the quality of seed, and involves the viability of the seed, the germination percentage, germination rate and the strength of the seedlings produced. The germination percentage is simply the proportion of seeds that germinate from all seeds subject to the right conditions for growth. The germination rate is the length of time it takes for the seeds to germinate. Germination percentages and rates are affected by seed viability, dormancy and environmental effects that impact on the seed and seedling. In agriculture and horticulture quality seeds have high viability, measured by germination percentage plus the rate of germination. This is given as a percent of germination over a certain amount of time, 90% germination in 20 days, for example. 'Dormancy' is covered above; many plants produce seeds with varying degrees of dormancy, and different seeds from the same fruit can have different degrees of dormancy. It's possible to have seeds with no dormancy if they are dispersed right away and do not dry (if the seeds dry they go into physiological dormancy). There is great variation amongst plants and a dormant seed is still a viable seed even though the germination rate might be very low. Environmental conditions effecting seed germination include; water, oxygen, temperature and light. Three distinct phases of seed germination occur: water imbibition; lag phase; and radicleRadicle In botany, the radicle is the first part of a seedling to emerge from the seed during the process of germination.... emergence. In order for the seed coat to split, the embryo must imbibe (soak up water), which causes it to swell, splitting the seed coat. However, the nature of the seed coat determines how rapidly water can penetrate and subsequently initiate germinationGermination Overview Germination is the process where growth emerges from a resting stage.... . The rate of imbibition is dependent on the permeability of the seed coat, amount of water in the environment and the area of contact the seed has to the source of water. For some seeds, imbibing too much water too quickly can kill the seed. For some seeds, once water is imbibed the germination process cannot be stopped, and if the seed dries out again it is fatal. Other species have seeds that can imbibe and lose water a few times without causing ill effects to the seed, and drying can cause secondary dormancy. Inducing germination A number of different strategies are used by gardeners and horticulturists to break seed dormancy. Scarification which allows water and gases to penetrate into the seed, include methods that physical break the hard seed coats or soften them by chemicals. Means of scarification include soaking in hot water or poking holes in the seed with a pin or rubbing them on sandpaper or cracking with a press or hammer. Soaking the seeds in solvents or acids is also effective for many seeds. Sometimes fruits are harvested while the seeds are still immature and the seed coat is not fully developed and sown right away before the seed coat become impermeable. Under natural conditions seed coats are worn down by rodents chewing on the seed, the seeds rubbing against rocks (seeds are moved by the wind or water currents), by undergoing freezing and thawing of surface water, or passing through an animal's digestive tract. In the latter case, the seed coat protects the seed from digestionDigestion For the industrial process see anaerobic digestion... , while often weakening the seed coat such that the embryo is ready to sprout when it gets deposited (along with a bit of fertilizer) far from the parent plant. MicroorganismMicroorganism A microorganism or microbe is an organism that is microscopic .... s are often effective in breaking down hard seed coats and are sometimes used by people as a treatment, the seeds are stored in a moist warm sandy medium for several months under non-sterile conditions. Stratification also called moist-chilling is a method to break down physiological dormancy and involves the addition of moisture to the seeds so they imbibe water and then the seeds are subject to a period of moist chilling to after-ripen the embryo. Sowing outside in late summer and fall and allowing to overwinter outside under cool conditions is an effective way to stratify seeds, some seeds respond more favorably to periods of osculating temperatures which are part of the natural environment. Leaching or the soaking in water removes chemical inhibitors in some seeds that prevent germination. RainRain Rain is a form of precipitation, other forms of which include snow, sleet, hail, and dew.... and melting snowSnow Snow is precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes.... naturally accomplish this task. For seeds planted in gardens, running water is best - if soaked in a container, 12 to 24 hours of soaking is sufficient. Soaking longer, especially in stagnant water that is not changed, can result in oxygen starvation and seed death. Seeds with hard seed coats can be soaked in hot water to break open the impermeable cell layers that prevent water intake. Other methods used to assist in the germination of seeds that have dormancy include prechilling, predrying, daily alternation of temperature, light exposure, potassium nitrate, the use of plant growth regulators like gibberellins, cytokinins, ethylene, thiourea, sodium hypochlorite plus others. Some seeds germinate best after a fire, for some seeds fire crakes hard seed coats while in other seeds chemical dormancy is broken in reaction to the presence of smoke, liquid smoke is often used by gardeners to assist in the germination of these species. Origin and evolution The origin of seed plants is a problem that still remains unsolved. However, more and more data tends to place this origin in the middle DevonianDevonian Disambiguation: "Devonian" is sometimes used to refer to the Southwestern Brythonic language, and the people of the county of De... . The description in 2004 of the proto-seed Runcaria heinzelinii in the GivetianGivetian The Givetian stage is the middle stage of the Middle Devonian period.... of BelgiumFacts About Belgium The Kingdom of Belgium is a country in northwest Europe bordered by the Netherlands, Germany, Luxembourg and France and is... is an indication of that ancient origin of seed-plants. As with modern ferns, most land plants before this time reproduced by sending spores into the air, that would land and become whole new plants. The first "true" seeds are described from the upper Devonian, which is probably the theater of their true first evolutionary radiation. The seed plants progressively became one of the major elements of nearly all ecosystems. Economic importance Edible seeds Many seeds are edibleList of edible seeds A variety of species can provide edible seeds.... and the majority of human calories comes from seeds, especially from cerealCereal Cereal crops are mostly grasses cultivated for their edible grains or seeds .... s, legumeLegume The term legume has two closely related meanings in botany, a situation encountered with many botanical common names of usef... s and nutNut (fruit) A nut is a seed of a plant. ... s. Seeds also provide most cooking oilCooking oil Cooking oil is purified fat of plant or animal origin, which is liquid at room temperature.... s, many beverages and spiceSpice A spice is a dried seed, fruit, root, bark or vegetative substance used in nutritionally insignificant quantities as a food ... s and some important food additiveFood additive Summary Food additives are substances added to food to preserve flavour or improve its taste and appearance.... s. In different seeds the seed embryoEmbryo An embryo is a multicellular diploid eukaryote in its earliest stage of development. ... or the endospermEndosperm Endosperm is a usually triploid tissue produced in the seeds of most flowering plants.... dominates and provides most of the nutrientNutrient A nutrient is any element or compound necessary for or contributing to an organism's metabolism, growth, or other functionin... s. The storage proteinProtein Proteins are large organic compounds made of amino acids arranged in a linear chain and joined by peptide bonds.... s of the embryo and endosperm differ in their amino acidAmino acid In chemistry, an amino acid is any molecule that contains both amine and carboxyl functional groups.... content and physical properties. For example the glutenGluten Gluten is an amorphous ergastic protein found combined with starch in the endosperm of some cereals, notably wheat, rye, and... of wheat, important in providing the elasticElasticity (physics) Elasticity is a branch of physics which studies the properties of elastic materials.... property to bread doughDough Summary Dough is a paste made out of any cereals or leguminous crops by grinding it with a small amount of water.... is strictly an endosperm protein. Seeds are used to propagate many crops such as cereals, legumes, forest treesForestry Forestry is the art, science, and practice of studying and managing forests and plantations, and related natural resources.... , turfgrasses and pasturePasture Pasture is land with lush herbaceous vegetation cover used for grazing of ungulate livestock as part of a farm or ranch.... grasses. Seeds are also eaten by animalAnimal Animals are a major group of organisms, classified as the kingdom Animalia or Metazoa.... s, and are fed to livestockLivestock Livestock is the term used to refer to a domesticated animal intentionally reared in an agricultural setting to make produce suc... . Many seeds are used as birdseed. Poison and food safety While some seeds are considered by some as healthy to eat, other seeds may be harmful or poisonous, Plants and seeds often contain chemical compounds to discourage herbivores and seed predatorsSeed predation Seed predation includes any process inflicted on a plants seeds by an animal that results in the inviability of the seed.... . In some cases, these compounds simply taste bad (such as in mustard), but other compounds are toxic, or breakdown into toxic compounds within the digestive system. Children, being smaller than adults, are more susceptible to poisoning or death by plants and seeds. One should be satisfied with reliable food safety information before choosing to eat any particular seeds. An infamously deadly poison, ricinRicin The protein ricin is a toxin from the castor bean.... , comes from seeds of the castor bean. Reported lethal doses are anywhere from two to eight seeds, though only a few deaths have been reported when castor beans have been ingested by animals. In addition, seeds containing amygdalinAmygdalin Amygdalin , C20H27NO11, is a glycoside isolated from bitter almonds by H.... ; appleApple The apple is a tree and its pomaceous fruit, of the species Malus domestica in the rose family Rosaceae.... , apricotApricot The apricot is a fruit-bearing tree native to China.... , bitter almond, peachPeach The Peach is a tree native to China that bears a juicy fruit of the same name.... , plumPlum "Plum" is also a nickname for British humorist P.G.... , cherryCherry Overview A cherry is both a tree and its fleshy fruit, a type known as a drupe with a single hard stone enclosing the seed.... , quinceQuince The Quince Cydonia oblonga is the sole member of the genus Cydonia and native to warm-temperate southwest Asia in th... , and others, when consumed in significant amounts, may result in cyanide toxicity. Other seeds than contain poisons include annonaAnnona Overview *Annona* is the type genus of the plant family Annonaceae.... , cottonCotton Cotton is a soft fiber that grows around the seeds of the cotton plant , a shrub native to the tropical and subtropical regi... , custard appleCustard apple Custard apple usually refers to:*Custard-apple, a fruit also called bullock's heart or bull's heart.... , daturaDatura *Datura* is a genus of 12-15 species of flowering plants belonging to the family Solanaceae.... , uncooked durianDurian Overview The durian is the fruit of trees belonging to the genus Durio.... , golden chain, horse-chestnut, larkspurDelphinium *Delphinium* is a genus of about 250 species of annual, biennial or perennial flowering plants in the buttercup family Ran... , locoweedLocoweed Locoweed is a term used to describe plants from two different genera of legumes most commonly found in the midwest.... , lycheeLychee Overview The Lychee, also spelled Litchi or Laichi, is the sole member of the genus Litchi in the soapberry family Sapindaceae.... , nectarine, rambutanRambutan The Rambutan is a medium-sized tropical tree in the family Sapindaceae, native to southeast Asia, and the fruit of this tre... , rosary pea, sour sop, sugar apple, wisteriaWisteria *Wisteria* is a genus of about ten species of woody climbing vines native to the eastern United States and the East Asian ... , and yewTaxus *Taxus* is a genus of yews, small coniferous trees or shrubs in the yew family Taxaceae.... . Another seed poison is strychnineStrychnine h colspan="2" align=center bgcolor="#cccccc">Strychnine... . The seeds of many legumes, including the common bean (Phaseolus vulgaris) contain proteins called lectins which can cause gastric distress if the beans are eaten without cookingCooking Cooking is an act of preparing food for eating.... . The common bean and many others, including the soybeanSoybean The soybean or soya bean is a species of legume native to eastern Asia.... , also contain trypsin inhibitors which interfere with the action of the digestive enzyme trypsinTrypsin Trypsin is in the family of serine proteases that cleave proteins at the carboxyl side of the amino acids lysine and argini... . Normal cooking processes degrade lectins and trypsin inhibitors to harmless forms. Other uses The world's most important clothing fiberFiber Summary Fiber or fibre is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to l... grows attached to cottonCotton Cotton is a soft fiber that grows around the seeds of the cotton plant , a shrub native to the tropical and subtropical regi... seed. Other seed fibers are from kapokKapok Kapok is a tropical tree of the order Malvales and the family Malvaceae , native to Mexico, Central America and the... and milkweed. Many important nonfood oils are extracted from seeds. Linseed oilLinseed oil Linseed oil is a yellowish drying oil derived from the dried ripe seeds of the flax plant.... is used in paints. Oil from jojobaJojoba Jojoba, pronounced "ho-ho'-b?", is a shrub native to the Sonoran and Mojave deserts of Arizona, California, and Mexico... and crambeFacts About Crambe *Crambe* is a genus of Brassicaceae native to Europe, southwest and central Asia and eastern Africa.... are similar to whale oilWhale oil Whale oil is the oil obtained from the blubber of various species of whales of the genus Balaena, as B.... . Seeds are the source of some medicines including castor oilCastor oil Castor oil is a vegetable oil obtained from the castor bean.... , tea tree oilTea tree oil Tea tree oil is a yellowish green-tinged essential oil with a fresh camphoraceous odour.... and the discredited cancer drug, LaetrileAmygdalin Amygdalin , C20H27NO11, is a glycoside isolated from bitter almonds by H.... . Many seeds have been used as beadBead A bead is a small, decorative object that is pierced for threading or stringing.... s in necklaces and rosaries including Job's tearsJob's Tears Job's Tears, Coixseed, adlay, or adlai, is a tall grain-bearing tropical plant of the family Poaceae nativ... , ChinaberryFacts About Chinaberry The Chinaberry or Bead Tree, is a deciduous tree in the mahogany family Meliaceae, native to India, southern China and... and rosary pea. However, the latter two are also poisonous. Other seed uses include: Seeds once used as weights for balanceWeighing scale Summary A weighing scale is a device for measuring the weight of an object.... s. Seeds used as toys by children, such as for the game conkerConker Conker is the name used in Britain, Ireland and some former British colonies for the nuts of the Common Horse-chestnut tree,... . Resin from ClusiaClusia *Clusia* is the type genus of the family Clusiaceae.... rosea seeds used to caulk boats. NematicideFacts About Nematicide A nematicide is a type of chemical pesticide used to kill parasitic nematodes.... from milkweed seeds. Cottonseed mealCottonseed meal Cottonseed meal is the byproduct remaining after cotton is ginned and the seeds crushed and the oil extracted.... used as animal feed and fertilizerFertilizer Fertilizers or fertilisers are compounds given to plants with the intention of promoting growth; they are usually app... . Trivia The oldest viableOldest viable seed There are several candidates for the oldest viable seed:... carbon-14Carbon-14 Carbon-14, 14C, or radiocarbon, is a radioactive isotope of carbon discovered February 27, 1940, by Martin Kamen... -dated seed that has grown into a plant was a Judean date palmJudean date palm The Judean date palm is a cultivar of the date palm.... seed about 2,000 years old, recovered from excavations at Herod the GreatHerod the Great Hordos , also known as Herod I or Herod the Great, was a Roman client- king of Judaea .... 's palace on MasadaMasada Masada is the name for a site of ancient palaces and fortifications in Israel on top of an isolated rock plateau on the eas... in IsraelIsrael Israel , officially the State of Israel, is a country in Western Asia on the southeastern edge of the Mediterranean Se... . It was germinated in 2005. The largest seed is produced by the coco de merCoco de mer The Coco de mer, the sole member of the genus Lodoicea, is a palm endemic to the islands of Praslin and Curieuse in the ... , or "double coconut palm", Lodoicea maldivica. The entire fruitFruit The term fruit has different meanings depending on context.... may weigh up to 23 kilograms (50 pounds) and usually contains a single seed. The earliest fossilFossil Fossils are the mineralized or otherwise preserved remains or traces of animals, plants, and other organisms.... seeds are around 365 million years old from the LateFamennian The Famennian is one of two faunal stages in the Late Devonian Period.... DevonianDevonian Overview Disambiguation: "Devonian" is sometimes used to refer to the Southwestern Brythonic language, and the people of the county of De... of West VirginiaWest Virginia West Virginia is a state of the United States in the region of Appalachia, also known as The Mountain State.... . The seeds are preserved immature ovuleFacts About Ovule An ovule is a structure found in seed plants that develops into a seed after fertilization.... s of the plantPlant Plants are a major group of living things including familiar organisms such as trees, flowers, herbs, ferns, and mosses.... Elkinsia polymorpha. See also Biological dispersalBiological dispersal Biological dispersal refers to those processes by which a species maintains or expands the distribution of a population.... GerminationGermination Germination is the process where growth emerges from a resting stage.... List of edible seedsList of edible seeds A variety of species can provide edible seeds.... Recalcitrant seedFacts About Recalcitrant seed Recalcitrant seeds are seeds that do not survive drying and freezing during ex-situ conservation.... Seed companySeed company Seed companies sell seeds for flowers, fruit and vegetables to the amateur gardener.... Seed orchardSeed orchard Overview A seed orchard is a plantation created for the production of genetically improved seeds to create plants, or direct seeding ... Seed predationSeed predation Seed predation includes any process inflicted on a plants seeds by an animal that results in the inviability of the seed.... SeedbedSeedbed A seedbed is a specially prepared area of the garden that has been made suitable for the sowing and germination of plant see... SeedlingSeedling A seedling is a young plant sporophyte developing out of a plant embryo from a seed.... StratificationFacts About Stratification (botany) In horticulture, stratification is the process of pretreating seeds to simulate natural conditions that a seed must endure b... External links : collecting, storing, sowing, germinating, and exchanging seeds, with pictures of seeds, seedpods and seedlings. seed structure, dormany, evolution, ecology, etc. - Pictures of Japanese plant seeds, fruits and etc. Kew Garden's ambitious preservation project - a backup facility for the world's seed banks