| Achene | A dry indehiscent one-seeded pericarp (e.g. lettuce). |
| Acorn | The fruit of the oak (Quercus spp.) and comprised of a nut and its cup or cupule. |
| After-ripening (in dry storage) | The loss in dormancy which occurs progressively when seeds are stored after harvest in the air-dry state. |
| Allogamous | Fertilization of the pistil of a plant by pollen from another of the same species. |
| Allotetraploid | Having four genomes with two sets (rarely one) coming from a different species than the others. |
| Amphicarpic | Where some flowers on a plant are cross-fertilized and others self-fertilized. |
| Amphidiploid | An organism or cell having a diploid set of chromosome from each parent (Synonym allotetraploid hybrid). A hybrid plant of two different species that has two sets of chromosomes from each of the parent species. |
| Andromonoecious | Species that have bisexual and male flowers on the same plant. |
| Anemophilous | Wind pollinated. |
| Apomictic | Asexual reproduction via sexual organs or related structures, but where fertilization does not occur, resulting in vegetatively produced seed. |
| Approach grafting | Grafting method where scion from the parent plant is not cut until after the graft has taken. |
| Aril | An appendage or an outer covering of a seed, growing out from the hilum or funiculus; it sometimes appears as a pulpy covering. |
| Autogamous | Self-fertilization, the fertilizing pollen deriving from the same blossom as the pistil acted upon. |
| Berry | Pulpy indehiscent few- or many-seeded fruit; technically the pulpy fruit resulting from a single pistil, containing one or more seeds (e.g. tomato) but no true stone. |
| Bisexual | Having both stamens and pistils. |
| Budding | Method of propagating woody plants. A cutting of one variety, termed the scion, with buds attached is joined on to another related species or variety, termed the stock. As the tissues grow together a single plant is formed with top-growth of the scion on the base of the stock. |
| Callus | Undifferentiated or unorganized cells produced from a plant explant on a culture medium. |
| Calyx | The outer circle of floral envelopes, comprised of the sepals; the latter may be distinct or connate in a single structure. |
| Caprification | Commercial process of pollination of fig plants by wasps. |
| Capsule | Compound pod; a dry fruit of more than one carpel, usually opening at maturity by one or more lines of dehiscence (e.g. poppy). |
| Carpel | Ovary, style and stigma; the structure bearing and enclosing the ovules. |
| Caruncle | A fleshy, sometimes coloured, appendage of the outer integuments for some seeds. |
| Caryopsis | An achene with pericarp and seed testa inseparably fused (e.g. Gramineae) |
| Catkin | A scaly-bract usually flexuous spike or spike-like raceme with diclinous flowers (e.g. willow). |
| Chasmogamous | Flowers or florets that are open at the time of fertilization or the opening of the perianth of a flower for the purpose of fertilization. |
| Cleistogamous | The condition of having flowers which self-pollinate in the bud, without the flower opening. |
| Cloves | A small bulb formed in the axil of the scales of a mother bulb, as in garlic. |
| Cold stratification | Also called pre-chill stratification. Seeds are placed in contact with a moist substratum and kept at low temperatures (3° to 10°C) for an initial period before being moved to the germination test temperature. |
| Cole crops | Members of the Brassicaceae family, formerly the Cruciferae; many are of the species Brassica oleracea.. |
| Cone | A dense and usually elongated collection of flowers or fruits that are borne beneath scales, the whole with scales and axis forming a detachable homogenous fruit-like body (e.g. pine). |
| Coppice | To cut a plant almost to the ground each year so as to produce more vigorous growth. |
| Corms | The enlarged fleshy base of a stem, bulb-like but solid. |
| Cotyledon(s) | The primary leaf (or leaves) in the embryo. |
| Cross-incompatibility | Occurs when pollen of one species fails to germinate on the stigma or grow in the style of another species. |
| Deciduous | A plant whose leaves are shed at a specific season or growth stage. |
| Dehiscence | The method or process of opening of a seed-pod; loculicidally dehiscent when the split opens into a cavity or locule; septicidally dehiscent when splitting along septum of the ovary; circumscissally dehiscent when the top valve comes off as a lid. |
| Dichogamy | The condition of certain species of plants, in which the stamens and pistil do not mature simultaneously, so that these plants cannot self-fertilize. |
| Dioecious | Unisexual, with male and female flowers on separate plants. |
| Dormancy | The condition in a viable seed which prevents it from germinating when supplied with those factors normally considered adequate for germination. |
| Drupe | A fleshy one-seeded indehiscent fruit with seed enclosed in a stony endocarp (stone-fruit) (e.g. Aleurites). |
| Drupelet | One drupe in a fruit made up of aggregate drupes (e.g. raspberry). |
| Embryo | The rudimentary plant within a seed, which arises from the zygote or sometimes from an unfertilized egg cell. It consists of an axis bearing an apical meristem or a plumule, a radicle, and one or more cotyledons. |
| Endocarp | The inner layer of the pericarp. |
| Endogamy | Self-fertilization. |
| Endosperm | Triploid tissue which develops from the fusion of a sperm nucleus with the two polar nuclei of the embryo sac. It supplies nutrients to the embryo and may be entirely used up during seed formation, or part of it may remain and sustain the seed during germination. |
| Entomophilous | Pollination by insects. |
| Exogamous | Cross-fertilization. |
| Facultative apomict | A plant that can reproduce either sexually or asexually (apomixis). |
| Facultative xenogamy | Delayed selfing. |
| Follicle | Dry dehiscent fruit opening only on the front suture and the product of a simple pistil (e.g. Delphinium). |
| Full bloom | Stage in flowering plants when the majority of the flower buds are opening. |
| Galls (swollen gum) | An abnormal localized swelling or outgrowth produced by a pla as a result of attack by a parasite. |
| Gametophitic self-incompatibility | A mechanism of avoiding self-fertilization whereby pollen-style interaction inhibits pollen tubes from growing. |
| Geitonogamy | The transfer of pollen to a stigma of a different flower on the same plant. |
| Germination | Ultimately the production of a seedling from a seed; the emergence of the radicle from the seed is normally the first visible sign that germination has commenced, but germination begins from the first metabolic process during imbibition. |
| Germination test | A laboratory test to estimate the proportion of seeds within an accession capable of germinating. |
| Grafting | Method of propagation for trees and shrubs by inserting a section of one plant, usually a shoot, into another so that they grow together into a single plant. |
| Gynodioecious | Both bisexual flowers and female flowers, but on separate plants. |
| Hardseededness | Hard seeds possess impermeable seed coats, and therefore cannot imbibe water and as a consequence cannot germinate. Reversible hard seeds (also known as conditionally hard seeds) soften if exposed to high relative humidity for a long time by the uptake of moisture over the whole seed coat. The seed coats of irreversible hard seeds do not soften if exposed to high humidity and remain hardseeded throughout germination tests (absolute hardseededness). |
| Herb | Plant naturally dying to the ground, without persistent stem above ground, and lacking definite woody firm structure. |
| Hermaphrodite | Having both male and female reproductive organs in the same flower. |
| Hermetic storage | Storage in an air-tight, moisture-proof container. |
| Heterostyly | Flowers are similar except that the stigmas and anthers are held at different levels relative to each other, because style length differs between plants. |
| Homogamous | Having all the flowers alike. |
| Homomorphic | Shaped similarly. |
| Host | A plant on which a parasite grows. |
| Inarching | Method of grafting used to replace the root system of an established tree for girdling of the original trunk, a delayed graft incompatibility freezing injury, or root system disease or pest problem. |
| Inbreeding | The process of self-pollination and self-fertilization. |
| Intermediate seed storage behaviour | A category of seed storage behaviour intermediate between those defined as orthodox and recalcitrant. For a detailed definition see Part IA, Section 5. Mature whole seeds are able to tolerate desiccation to seed moisture contents in equilibrium at 20°C with about 40-50% relative humidity but further desiccation often reduces viability and always results in more rapid deterioration in subsequent hermetic storage the more the seeds are dried below this value. |
| Isolation distance | Distance required to isolate cultivars of a species to avoid cross-pollination. |
| Juvenile stage | Young plants. |
| Long-term storage | The storage of seed accession for long-term periods (a decade at a minimum, but many such stores expect satisfactory storage for 50-100 years or more). Stores operated at subzero temperatures are generally classed as long-term seed stores, but the storage conditions recommended by IPGRI (formerly IBPGR) for long-term seed conservation are –18°C or less in air-tight containers at a seed moisture content of 5 ± 1%. (w.b.) (Cromarty et al., 1982). |
| Longevity, Life span | In seeds, it is the length of time that they remain viable. The life span depends on the species and the environmental conditions under which the seeds are stored. The duration is often qualified by the percentage of seed viability at the end of the period because seedlots are populations in which some seeds die sooner than others (e.g. 85% viability in order to ensure that the majority of individuals in the seed population are viable and in good condition at the end of this period). |
| Male sterility | Absence of or non-functioning pollen. |
| Marcotting | An exceptional method of forcing the branch of a tree to form its own root system. |
| Medium-term storage | The storage of seed for medium-term periods as is often used for active collections in genebanks or by plant breeders and seedsmen. Under the same conditions of storage, the seeds of different species will have different periods of longevity. Thus it is difficult to define precisely the period envisaged by ‘medium-term’. A period of 2-10 years or so is generally assumed. As a guide, stores which are run at temperatures between 0 and 10°C have been listed as medium-term stores. |
| Mixed mating | Mode of reproduction in plants where cross-pollination and self-pollination takes place in plants of the same species (e.g. Hevea brasiliensis). |
| Monocarpic | Plants that die after first flowering. |
| Monoecious | Having stamens and pistils in separate flowers on the same plant (e.g. Zea mays). |
| Nut | An indehiscent, one-seeded, hard and bony fruit, even if resulting from a compound ovary (e.g. Corylus). |
| Nutlet | A small nut. |
| Obligate apomict (diplospory) | Plants that can only reproduce through apomixis (see apomictic). |
| Obligatory | Mandatory. |
| Open storage | Storage conditions where seeds are exposed directly or indirectly to ambient relative humidity (and sometimes also temperature); for example, in a paper bag, cloth bag, or a similar material which permits seed moisture content to be influenced by ambient relative humidity. |
| Orthodox seed storage behaviour | Mature whole seeds not only survive considerable desiccation (to at least 5% moisture content) but their longevity in air-dry storage is increased in a predictable way by reduction in seed storage moisture content and temperature (e.g. to those values employed in long-term seed stores). |
| Outbreeding | Cross-pollination. |
| Ovary | Part of the pistil that contains the ovules. |
| Ovule | The "egg" in the ovary which, after fertilization becomes the seed. |
| Parthenocarpy | The production of fruits without fertilization. |
| Perianth | The collective term for the calyx and corolla. It is made up of one or more whorls of floral leaves (petals and sepals). |
| Perianth | The floral envelope, consisting of the calyx and corolla (when present). |
| Pericarp | The fruit wall which has developed from the ovary wall. The pericarp comprises the endo-, meso- and exocarps. There are various forms such as dry, fleshy and woody pericarps. |
| Pernicious weed | Destructive weed. |
| Pistils | Either a single carpel or fused group of carpels. |
| Pod | A dehiscent dry pericarp. |
| Pollen | Spores of a seed plant contained in the anther, usually appearing as a fine dust. |
| Pollination | Transfer of pollen from the anther of a stamen to the stigma of a pistil, resulting in fertilization. This can occur either on a single plant (self-pollination) or between different plants (cross-pollination). |
| Polygamous | Both hermaphroditic and unisexual flowers on the same plant or on separate plants of the same species. |
| Polyploids | Having more than two sets of chromosomes in cells of the sporophyte or more than one set in cells of the gametophyte. |
| Pome | A fruit in which the multiseeded core is surrounded by a papery endocarp which, in turn, is fused to the fleshy receptacle (e.g. apple). |
| Pre-chill stratification | Also called cold stratification. Seeds are placed in contact with a moist substratum and kept at low temperatures (3° to 10°C) for an initial period before being moved to the germination test temperature. |
| Pre-dry | Before imbibition the dry seeds are heated at a temperature not exceeding 40°C with free air circulation for up to 7 days, depending on species and dormancy. |
| Pre-soak | Seeds are soaked in static water. |
| Pre-wash | Seeds are soaked and washed in running water at between 20° and 25°C for 2 hours or so to remove substances in seed (or fruit) coats which may inhibit germination. |
| Preferred storage conditions | The storage conditions recommended by FAO and IPGRI (formerly IBPGR) for long-term seed conservation, viz. storage at –18°C or less in air-tight containers at a seed moisture content of 3-7% (w.b.) (http://www.ipgri.cgiar.org/Publications/pubfile.asp?ID_PUB=424) |
| Protandrous | A flower where the shedding of pollen occurs before the stigma is receptive. |
| Protogynous | The stigma of an individual flower is receptive to pollen before its anthers release pollen. |
| Pseudogamy | The stimulation of development of seed formation by pollination. |
| Pyrene | The stone of a small drupe. |
| Recalcitrant seed storage behaviour | Mature whole seeds are unable to tolerate more than a limited amount of desiccation, for example to moisture contents in equilibrium at 20°C with about 96-98% relative humidity or a seed water potential of around –1.5 to –5 Mpa. |
| Rhizomes | Any prostate or subterranean stem, usually rooting at the nodes and becoming erect at the apex. |
| Ripening | The maturing of a fruit as developmental changes prepare it for seed dispersal. |
| Rootstocks | The root system and lower portion of a woody plant to which a graft of a more desirable plant is attached. |
| Samara | Indehiscent winged fruit (e.g. Acer). |
| Scarification | Seed coats are altered by abrasion in order to remove hardseededness. Scarification may be mechanical, by hand or machine, by immersion in acid, or by immersion in a solvent. |
| Schizocarp | A dry dehiscent fruit that splits into two halves, each half a mericarp (e.g. Umbelliferae). |
| Scions | Cutting from the upper portion of a plant that is grafted on to the rootstock of another plant, usually a related species. |
| Self-incompatibility | Mechanism of avoiding inbreeding. |
| Shield budding | Method of propagating woody plants. |
| Shrub | A woody plant that remains low and produces shoots or trunks from the base. |
| Sib-pollination | Self-pollination or crossing between genetically similar parents. |
| Siliqua | The long fruit of certain Cruciferae. |
| Spikelet | The seed bearing part of a small-grain cereal plant (e.g. wheat). |
| Sporophytic self-incompatibility | Rejection of self-pollen is controlled by the diploid genotype of the sporophyte generation. |
| Stamens | One of the male pollen-bearing organs of the flower. |
| Stecklings | Rooted cuttings or young carrot roots. |
| Stigma | Part of a pistil through which fertilization by the pollen is effected. |
| Stolon | A specialized type of horizontal above-ground shoot, a colonizing organ that arises from an axillary bud near the base of the plant. |
| Stumps | Projecting remnant of cut or broken tree. These sprout if left in the ground. |
| Style | Usually attenuated portion of the pistil connecting the stigma and ovary. |
| Suckers | A shoot from the root or lower part of a stem. |
| Thrips | Insects (e.g. Frankliniella occidentalis) that feed inside developing flower buds and in newly expanding leaves of plants. |
| Topsets (bulbils) | A small bulb or bulb-shaped body, especially one borne upon the stem, and usually produced for asexual reproduction. |
| Tree | A woody plant that produces one main trunk and a more or less distinct and elevated head. |
| Trellis | A frame of latticework used as a screen or as a support for climbing plants. |
| Tripping | Facilitation of pollen transfer and stigma receptivity by insects such as honeybees and bumblebees. |
| Tristylous | A flower that has styles of three different lengths. |
| Unisexual | A flower of one sex only, either pistillate (female) or staminate (male). |
| Utricle | A bladdery one-seeded and usually indehiscent fruit (e.g. Basella). |
| Vernalization | Cold temperature treatment (often lasting 2 to 6 weeks) required by some seedlings to induce reproductive growth. |
| Viability | The possession in a seed of those processes essential for a seed to germinate. Thus a viable seed is alive; but this does not ensure that the seed will germinate (for example, if the seed is dormant). Within an accession, percentage viability is the proportion of seeds which are viable; it is estimated from the result of a viability test. |
| Viability test | A test on a sample of seeds withdrawn from the accession designed to estimate the percentage viability of the accession. A germination test can only function as a viability test either if all the seeds are non-dormant, or if special treatments are applied to remove dormancy. An alternative viability test procedure which does not require special treatments to remove dormancy is the tetrazolium test (vital stain); in forest tree seed testing the term viability test is often synonymous with a tetrazolium test. |
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