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Abscission - separation of an organ from a plant.

Accessory - a term given mostly to aggregate fruits in which the conspicuous and often edible portion is non-ovarian in origin. Example - strawberry, where the receptacle is the fleshy, edible portion, and the true fruit an achene.

Achene - a dry, indehiscent, one- or two-seeded fruit, with generally thin pericarp loosely attached to the seed(s). Fruit is generally small, and comes from a unicarpellate ovary. Example - sunflower, where the thin, black pericarp (shell) surrounds the single seed.

Acre - unit of land area equal to 43,560 ft²

Adventitious roots, buds - organs which arise from tissues unrelated to the normal hypocotyl- and radicle-derived meristems; i.e., roots or buds arising from the vascular cambium, cortex, phloem parenchyma, or wound callus.

Aggregate - a fruit derived from two or more ovaries contained within a single flower; may contain non-ovarian tissue. Example - blackberry, where each fruit is an aggregate of drupelets attached to a common receptacle. Raspberry is also an aggregate of drupelets but does not contain receptacle tissue.

Albedo - The mesocarp of a citrus fruit; the white, spongy tissue lying between the colored peel and the juice sacs.

Alternate bearing (syns biennial bearing, irregular bearing) - high production of fruit one year followed by low production the next. Common in nut trees.

Androecium - the stamens of a flower, collectively.

Anther - The swollen, apical, pollen-bearing section of the stamen.

Anthesis - Time of flower expansion when pollination takes place.

Anthocyanin - a class of water-soluble pigments responsible for the red, purple, and blue coloration of flowers and fruits.

Apomixis, apomictic seed (Syn agamospermy) -  reproduction of a plant through a seed wherein the embryo has arisen clonally from nucellar or integument tissue, and is genetically identical to the parent plant.

Asexual - without sex, as in vegetative reproduction or propagation.

Auxin - a class of plant growth regulators used in fruit crops primarily to root cuttings, chemically thin fruit, and prevent pre-harvest drop of fruit.

Axil - the angle formed at the point of insertion of a leaf to a stem.

Axillary bud - a bud found in a leaf axil.

Bearing habit - The position of the flower buds, with respect to the type and age of wood. For example, “spur bearing” trees produce flowers (thus fruits) on short, long-lived, lateral branches called spurs.

Bench Graftage - Grafting technique where the union is made at a propagation bench instead of a potted or soil-rooted plant; involves storage and callusing of rootstock and scion wood during the winter, and specialized cuts made with special tools or saws. Common with grape.

Berry - a fleshy, indehiscent fruit with more-or-less homogeneous texture throughout, derived from a single, superior ovary. One- to many-seeded. Example - grape. Term often misused. An epigynous berry is same derived from an inferior ovary (like blueberry).

Bisexual (syns hermaphroditic, perfect) - having both sexes present.

Bloom - epicuticular wax found on the surface of a plant organ, particularly fruits. Also, used as synonym for flower or anthesis (which see).

Bract - A modified leaf structure that subtends a flower or inflorescence.

Brambles - a group of fruit crops in the genus Rubus. Includes blackberries, raspberries, and hybrids thereof.

Bud - an undeveloped vegetative shoot, flower, or inflorescence; borne laterally or terminally on stems.

Budding - Means of vegetative propagation where the scion is reduced to a single bud, usually axillary, which is inserted into a rootstock. Main types used for fruit trees are T-budding and chip budding.

Bur (also Burr) - A spiny appendage; the involucre of a chestnut fruit.

Burrknot - concentration of preformed root initials on a stem or the trunk; can cause partial girdling and stunting of the tree.

Bushel - a unit of measurement of fruit yield, equal to about 50 lbs. Generally, wooden baskets or boxes are used, with a volume of about 1/28th of a cubic meter.

CA storage - see Controlled Atmosphere storage

Callus - undifferentiated, swollen tissue, often found at the site of a wound.

Calyptra - a hood or lid; specifically, the corolla of a grape flower fused at its apex.

Calyx - the sepals, collectively.

Cane - an elongated, flexible stem, coming from the ground in Rubus and blueberry, or from older wood as in grape.

Canopy - the foliage- and fruit-bearing portion of a crop plant.

Capsule - a dry, dehiscent, one- to many-seeded fruit from a compound ovary (compound = multiple locules within ovary). Subcategories are organized by dehiscence: circumscissile, loculicidal, septicidal, etc. Often irregularly shaped. Example - poppy.

Carpel - the megasporophyll, or structure enclosing the ovules (seeds). If a simple ovary, then the carpel and ovary are the same structure. If a compound ovary, then it is comprised of 2 or more carpels.

Caryopsis - small, indehiscent, one-seeded fruit, often dry and mealy at maturity, with pericarp fused to seed coat. Example - small grains (wheat, maize, barley, etc.).

Catfacing - injury to fruit, generally from insects, resulting in severe distortion of fruit shape. Occurs when an area of the surface of a young fruit is injured, killing the tissue, but surrounding healthy tissue continues to grow and develop.

Catkin - a slender, flexible, pendulous spike.

Cauliflory (cauliflorous) - a term applied to plants that bear flowers and fruit on main stems or trunks, such as cacao, jackfruit, and jaboticaba.

Central leader - A tree training system where a main central bole (the “leader”) extends from the trunk to the top of the tree. At intervals along the central leader, tiers of fruiting scaffolds are trained, with the lowest tier extending the furthest, and the upper tier extending only a few feet, giving an overall shape like a Christmas tree.

Chasmogamous - Flowers that must open before pollination; opposite of cleistogamous. Often seen in cross-pollinating species.

Chlorosis - yellowing of the foliage.

Chilling injury - injury from prolonged exposure to low, non-freezing temperatures. Commonly affects tropical fruits. Results in discoloration, pitting, and flesh breakdown in susceptible species.

Chilling requirement - The time of exposure to cool, nonfreezing temperatures during winter required to allow normal budbreak and development the following spring. Measured in hours at or below 45°F from approximately leaf drop in fall throughout the winter.

Circumscissile capsule (syn Pyxis) -  a dry, dehiscent, one- to many-seeded fruit from a single, compound ovary, opening at the equator, with the top separating like a lid.

Cleistogamous (cleistogamy) -  Self-pollinating nature of closed flowers. Opposite of chasmogamous.

Clingstone - adherence of the flesh (mesocarp) to the pit (endocarp) in a drupe or stone fruit. Also used to denote a group of peach cultivars used for canning that carry this trait.

Clonal - said of a plant derived from some form of vegetative propagation. Example - a clonal rootstock is one produced by layerage, division, cuttage, but not by seed.

Cold hardiness (Cold hardy) - minimum temperature tolerance of a plant, usually given in °C or F causing death or severe injury.

Compatibility (congeniality) - capable of coexisting; said of a rootstock and scion that unite and form a healthy, long-lived tree.

Complete flower - A flower having a calyx (sepals), corolla (petals), androecium, and gynoecium.

Compound - an organ composed of multiple parts, as a compound leaf where the blade is composed of leaflets, or a compound ovary divided into 2 or more carpels.

Compound spadix - an inflorescence composed of multiple branches with a more or less common point of attachment, each of which is a spadix. The inflorescence type of many palms.

Controlled Atmosphere storage - subjecting fruit to low oxygen and high carbon dioxide during cold storage to extend postharvest life.

Cordon - a permanent, horizontally trained limb; most commonly used in grapes to denote the major scaffolds.

Corm - a shortened, vertically oriented, solid underground stem.

Corolla - the petals, collectively.

Corymb - an indeterminate inflorescence where flowers are born in a plane or slight arc. The pedicels of lowermost flowers are elongated and those of uppermost flowers shortened so that all flowers are displayed at about the same height (ex - pear). Similar in shape to an umbel but with pedicels arising from different points on the main axis.

Cross-compatible - Pollen of one plant is capable of fertilizing ovules of another, genetically distinct plant.

Cross-pollination - pollen transfer between the anther and stigma of two genetically distinct plants.

Cross-sterile - inability of a plant to produce fruit with viable seed when cross-pollinated by another genetically distinct plant; does not preclude parthenocarpic fruit set and development.

Cross-unfruitful - a genetically distinct plant is used as a pollinizer for another plant and the latter fails to produce a commercial crop.

Culling (n. Cull) - removal of defective or unmarketable fruit post-harvest.

Cultivar - A cultivated variety, or subspecies of a plant. Often used interchangeably with variety in the field.

Cutting - organ isolated from a plant prior to root (stem cutting) or shoot (root cutting) development.

Deciduous - plant which loses its foliage annually.

Dehiscence - Natural splitting or opening of organs (dry fruits, anthers) causing the contents to be released.

Delayed dormant spray - a pesticide application applied to trees when buds have begun to swell, but new tissues are not yet fully exposed.

Delayed incompatibility - a situation where a rootstock and scion appear to be compatible and grow vigorously for several years, after which time the tree declines and may eventually break cleanly at the graft union.

Determinate - term applied to inflorescences having the top-most or central flower appearing and maturing first in the blooming sequence.

Dichasial cyme (syn. Dichasium) - a cymose inflorescence where the lateral axes split into multiple flowers (strawberry).

Dichogamy - Prevention of self-pollination by temporal separation of pollen shed and stigma receptivity. Includes protandry, protogyny, and synchronous protogyny (which see).

Dioecious - when staminate and pistillate flowers are borne on separate plants (Date, Pistachio, Kiwifruit).

Division - a form of propagation where a complete plant develops while still attached to the parent plant.

Dormancy - a temporary suspension of visible growth in organs containing meristems; occurs each winter in temperate fruit trees.

Dormant oil - an important spray material for most fruit trees; emulsifiable oil is mixed with water and applied to trees before buds swell, killing many overwintering pests.

Dormant pruning - pruning during the dormant season.

Double budding - placing a thin sheath of wood between the rootstock and scion bud to serve as a compatibility bridge. Results in a tree with an extremely short interstem.

Double fertilization - In angiosperms, the union of one generative nucleus from a pollen grain with the egg, yielding a 2n zygote; AND the union of the other generative nucleus from a pollen grain with the two polar nuclei, yielding 3n endosperm.

Drupe - a fleshy, indehiscent, usually one-seeded fruit with a hard, woody endocarp surrounding the seed. The "stone" (endocarp) often confused for the seed, called a pit or pyrene.  A drupelet = small drupe. Example - peach.

Dwarfing rootstock - a rootstock that reduces the potential size and/or vigor of the scion relative to a seedling rootstock.

Effective pollination period - The window of time that pollination can occur and effect fertilization. Can be calculated as the longevity of the embryo-sac minus the time required for pollen germination on the stigma and pollen-tube growth.

Egg nucleus - One of eight nuclei contained within the embryo sac. It fuses with a generative nucleus from a pollen grain, and develops into the zygote and ultimately the embryo within a seed.

Embryo sac - the 8-nucleate cell in the ovule that contains the egg and polar nuclei, and develops into the embryo and endosperm.

Endocarp - the innermost tissue layer of the ovary; often becoming specialized, like the pit of a peach.

Endosperm - The nutritive tissue surrounding the embryo in a seed; created by fusion of one generative nucleus with two polar nuclei during double fertilization. Often absorbed by the cotyledons during seed maturation in dicots.

Endosperm incompatibility - prevention of successful double fertilization caused by  the failure of one generative nucleus to unite with the polar nuclei and produce endosperm.

Enology - the study of wine making.

Epigynous - inferior ovary position. The point of attachment of the sepals, petals, and stamens is above the ovary.

Epigynous berry - a berry-like fruit derived from an inferior ovary.

Even pinnate - even number of leaflets in a pinnately compound leaf.

Exocarp - outermost tissue layer of the ovary; often becoming all or part of the fruit skin or peel.

Feathered - said of a nursery tree having branches (contrast whip).

Fecundity - the capacity of a plant for production of great quantities of viable seed.

Fertilization (syn. Syngamy) - The union of a male gamete contained in the pollen grain with the female gamete (egg) in the ovule.

Filament - the stalk of a stamen; organ that holds the anther at its tip.

Flavedo - the exocarp of a citrus fruit. The thin, colored part of the rind, containing the oil glands.

Floral initiation - The first discernable change from a vegetative apex to a reproductive apex; biochemical in nature, not visible under microscope.

Follicle - a dry, dehiscent, simple, one- to many-seeded fruit dehiscing via only one suture. Example - milkweed.

Freestone - separation of the flesh (mesocarp) from the pit (endocarp) in a drupe or stone fruit. Also used to denote a group of peach cultivars used for fresh market that carry this trait.

Frost pocket - a low-lying, frost-prone area of the landscape.

Fruit - A matured ovary plus any associated parts (such as receptacle, calyx, peduncle, or corolla tissue).

Fruitlet - a young or diminutive fruit, just after fruit set.

Fruit crop - a perennial, edible plant cultivated for its true botanical fruit or products derived therefrom.

Fruit set - persistence and development of an ovary after flowering.

Frutescent - describes a woody plant which is shrubby in habit.

Functionally dioecious - term applied to a monoecious plant when there is a complete temporal separation of pollen shed and stigma receptivity.

Generative nucleus - the genetic material of the pollen-bearing plant which goes on to unite with either the egg nucleus or the polar nuclei in the process of double fertilization; each pollen grain contains two generative nuclei.

Germplasm - the genetic variability of a population of organisms. Physically, any plant part containing genetic information that can be used by nurserymen, breeders or genetic engineers to improve or alter a plant species.

Gibberellic acid (GA, gibberellins) - a class of growth hormone that stimulates cell elongation and growth in general. Uses in fruit crops include bloom delay, reduction of flowering, and parthenocarpic fruit set.

Girdling - removal of a complete strip of bark from a stem or branch to impede phloem transport. Sometimes used to improve fruit set or size.

Glabrous - smooth, hairless surface.

Glaucous - covered with bloom (epicuticular wax).

Grafting - Means of vegetative propagation where the scion is one or more buds attached to a section of stem; methods of uniting stock and scion are more numerous and detailed than budding.

Graft union - the point at which rootstock and scion are united.

Grove - a chance or natural planting of fruit crops; generally not designed or uniformly spaced. Term often incorrectly used for Orchard.

Growing degree hours - an unit of measure of the amount of hours above 40°F (4.5°C) that a plant receives during dormancy after its chilling requirement is satisfied.

Ground color - the background color of fruit skin, generally green or yellow. Contrast with the blush color or the skin near maturity, which is generally red.

Gummosis - exudation of gums and resins, generally from the wood of a tree; a nonspecific malady, caused by fungi, bacteria, insects, mechanical damage, etc., frequently seen in stone fruits.

Gynoecium - the female parts of the flower; the pistils, collectively.

Half-inferior - see perigynous.

Heading back (syn heading, heading cut) - pruning a limb at a point somewhere along its length. Some portion of the limb remains.

Hectare - unit of land are equal to 10,000 m², or about 2.4 acres.

Hermaphroditic (syn perfect, bisexual) - having anthers and pistils in the same flower.

Hesperidium - a fleshy, indehiscent fruit with a leathery or hard rind; flesh divided into several segments by thin septa. Example - citrus.

Heterodichogamy - having flowers of different sexes that are functional at different times on the same plant.

Heterogamy  - having flowers of differing sex on the same plant (monoecious).

High density orchard - an orchard planting design with several hundred to thousands of trees per acre. Trees spaced much closer than in conventional orchards.

Hydrocooling - initial post-harvest handling practice where cold water is used to rapidly reduce fruit temperature.

Hypanthium - the floral cup; fusion of the bases of the sepals, petals, and stamens into a continuous, cup-shaped structure surrounding the ovary.

Hypogynous - superior ovary position. The point of attachment of the sepals, petals, and stamens is below the ovary.

IAA - indole acetic acid; see auxin.

Imperfect flower - lacking one of the two sex organs, the androecium or gynoecium.

Incompatibility - with reference to pollination, inability to successfully fertilize an ovule and produce  seed. With reference to grafting; a scion/rootstock combination incapable of coexisting. See also delayed incompatibility, endosperm incompatibility, nuclear incompatibility, and pollen tube failure.

Incomplete flower - lacking one or more of the following: calyx (sepals), corolla (petals), androecium, gynoecium.

Indehiscent - not splitting open at maturity.

Inflorescence - a cluster of flowers.

Infructescence - a ripened inflorescence.

Indeterminate - descriptive term applied to inflorescences having the top-most or central flower appearing and maturing last in the blooming sequence.

Inferior ovary - epigynous ovary position (which see).

Integrated pest management (IPM) - A pest management method that utilizes all  techniques of pest control (e.g., cultural, biological, chemical, etc.) in an integrated fashion to keep pest populations below an economic threshold level. [see chapter 2].

Integuments - the outermost part of the embryo sac, which develop into the seed coat.

Internode - the space between 2 nodes on a stem.

Interspecific - between two species, such as a hybrid.

Interstock (Interstem) - a stem piece inserted between a rootstock and a scion.

Involucre - bract(s) subtending a flower or inflorescence; can be leafy (hazelnut), fleshy (walnut), or woody (cup of an oak acorn).

June drop - shedding of fruits in May or June due to competition for resources; reduced by thinning.

Juvenility - stage of life cycle where flowering/fruiting is not yet possible.

Lateral - an elongated shoot coming from a main shoot; also used to denote a fruit bearing habit where fruits arise from axillary buds on elongated shoots.

Leader - the main axis or central bole of a tree.

Legume (syn. pod) - a dry, dehiscent, simple, one- to many-seeded fruit, with dehiscence via 2 sutures, ventral and dorsal;. Example - bean.

Liana - a woody vine.

Locule - the seed cavity; then central, open portion of a carpel.

Loculicidal capsule - a dry, dehiscent, one- to many-seeded fruit from a single, compound ovary, opening through the locules.

Loment - a dry, dehiscent, simple, many-seeded fruit that is constricted between the seeds; dehiscence is via 2 sutures, as with a legume.

Mesocarp - the middle tissue layer of an ovary.

Metaxenia - effects of the pollen source on the fruit tissues exclusive of the seeds.

Metric ton - One thousand kilograms, or 2200 lbs.

Mixed bud - a bud possessing both flowers and leaves, as opposed to a simple bud that contains either flowers or leaves.

Monoecious - A plant having separate male and female flowers.

Multiple fruit - fruit produced by the fusion or adherence of two or more ovaries arising from different flowers; a fused inflorescence. Examples - pineapple and mulberry. Sometimes termed a syncarp (syn. syncarpium) if it contains non-ovarian tissues, as it usually does.

NAA - Naphthalene acetic acid; a synthetic auxin used to thin fruitlets in the spring, or ironically, to prevent fruit abscission just before harvest.

Necrosis (necrotic) - death of organs or tissues

Nectary - organ that secretes nectar, usually at the base of the ovary in flowers.

Nematocide - a chemical that kills nematodes.

Nematode - a microscopic, non-segmented round worm; a root pest of fruit crops.

Node - the point of origin of buds or leaves on the stem.

Nucellar embryony - Adventitious embryos arise from the nucellus, yielding embryos genetically identical to the mother plant.

Nucellus - maternal (2n) tissue surrounding the embryo sac in an ovule.

Nuclear incompatibility - lack of seed and possibly fruit set due lack of fusion of the egg and generative nuclei during double fertilization.

Nut - a dry, indehiscent, one-seeded (usually) fruit with a hard exterior. Example - pecan, walnut.

Odd pinnate - odd number of leaflets in a pinnately compound leaf.

Open center - A tree training system where 3-5 main structural limbs (scaffolds) radiate in all directions from a stout trunk 1-3 ft tall. No structural limbs grow in the center of the canopy. Often used with trees having weak apical control and tend to form rounded canopies naturally (e.g., peach, plum, apricot, almond).

Orchard - a regularly spaced, geometric planting of fruit crops. (Contrast grove).

Organic acids - natural acidic compounds found in fruit pulp and juice. Most commonly citric acid and malic acid, but dozens of forms exist. They make fruit tangy and/or sour.

Ossiculus (syn pit, pyrene) - see pyrene.

Ovary - The swollen base of the pistil, containing the ovules; matures into the fruit.

Ovule - an immature seed; the embryo sac surrounded by the integuments and nucellus.

Own-rooted scion - fruit tree propagated vegetatively by layering or cuttings; the tree's root system is produced adventitiously from mature scion wood.

Palmate - radiating out from a common point, as with leaflets in palmately compound leaves.

Panicle - a multiply branched, indeterminate inflorescence with 2 or more orders of laterals (mango).

Parthenocarpy (parthenocarpic) - Fruit development in the absence of fertilization and seed production. Vegetative parthenocarpy is the form where pollination need not occur for fruit set, whereas stimulative parthenocarpy is the form where pollination stimulates fruit set, yet fertilization does not occur.

Pedicel - the stalk of a flower.

Peduncle - the stalk supporting the entire inflorescence or a single fruit.

Penetrometer - device for measuring the firmness of fruit flesh.

Pepo - a fleshy fruit from a compound, inferior ovary, with a thick, tough rind. Distinguished from a hesperidium by having parietal placentation instead of axile, and coming from an inferior ovary. Example - watermelon (most Curcurbitaceae).

Perennial - a plant capable of living more than two years.

Perfect flower (syn hermophroditic) - A flower having both male and female parts.

Perianth - the calyx and corolla together.

Pericarp - the wall of the fruit derived from ovary tissue. Divided into three histogenic layers: exocarp - outermost, mesocarp - middle, endocarp - innermost.

Perigynous - half-inferior ovary position. The point of attachment of the sepals, petals, and stamens surrounds the ovary.

Pest - any organism that reduces yield and/or crop quality.

Petal - a member of the corolla; a floral appendage, often showy.

Petal fall - stage of floral development after anthesis when petals abscise. Often used as visual cue for spray timing.

Pheromone - a chemical insects use for mating and communication.

Phloem - the photosynthate conducting tissue of plants; just beneath the bark and outside of the wood of a stem.

Photosynthate - end products of photosynthesis; sugars mostly.

Phyllotaxy - the arrangement of leaves on a stem. Denoted as a fraction, where the numerator is the number of revolutions around the stem, and the denominator is the number of nodes between two leaves with the same vertical orientation.

Phytotoxic - a chemical that is poisonous to crop plants.

Pilose - covered with soft, long hairs.

Pinnate - with subdivisions arranged oppositely along a main axis in pairs; as in pinnately compound leaves.

Pistil - The female reproductive organ of the flower, composed of the stigma, style, and ovary.

Pistillate - said of a flower or plant containing the gynoecium or pistil(s).

Pit - the endocarp, or stone in a drupe.

Placenta (placentation) - portion of the ovary to which the ovules are attached. Arranged in several ways: axile, basal, free central, or parietal.

Pod - see legume.

Polar nuclei - Two of the eight nuclei contained in a mature embryo sac which form the endosperm of the seed after uniting with one generative nucleus from the pollen.

Pollen (grain) - the male gametophyte of an angiosperm or gymnosperm; tiny structure carrying haploid, generative nuclei.

Pollen tube - An elongated, narrow, tubular structure arising from a germinated pollen grain. It grows through the style and carries the generative nuclei toward the egg sac of the ovule.

Pollination - transfer of pollen from the anther to the stigma.

Pollinator - an agent of pollen transfer; generally honey bees, or the wind in wind-pollinated species.

Pollinizer (pollenizer) - with reference to cross-pollinated species; a cultivar that functions as a source of compatible pollen.

Polyembryony - two or more embryos arising from a single seed.

Polygamous - having unisexual and bisexual flowers on the same plant.

Polygamodioecious - primarily dioecious, but having some bisexual flowers or flowers of the opposite sex on the same plant.

Polygamomonoecious - primarily monoecious, but having some bisexual flowers.

Pome - a fleshy, indehiscent fruit from an inferior, compound ovary, generally having a cartilaginous endocarp; the fleshy receptacle or hypanthium completely enclosing and fused to the pericarp. Example - apple.

Pome fruits - a group of crops having a pome as a fruit type; members of the Pomoideae subfamily of the Rosaceae (apple, pear, quince, others).

Pomology - the study of fruit culture.

Pomologist - one who studies fruit culture.

Poricidal capsule -  a dry, dehiscent, one- to many-seeded fruit from a single, compound ovary, opening through pores or flaps.

Precocious (n. Precocity) - advanced in development; said of a species with a short period of juvenility. Flowers and bears fruit at a young age.

Primocane - the current season’s shoot that comes from the ground in brambles; vegetative in most cases, except primiocane-fruiting raspberries.

Protandry (Protandrous) - Pollen is shed before the stigma is receptive.

Protogyny (Protogynous, syn Metandry) - The stigma is receptive before pollen is shed.

Pruning - removing limbs or stems from a plant.

Pubescent - possessing fine hairs on the surface.

Pulp - the edible or juice-containing portion of the fruit.

Pyrene (syn ossiculus) - the hard pit of a stone fruit; bony endocarp.

Pyriform - pear-shaped.

Pyxis - a circumscissile capsule.

Quiescence - a dormant condition brought on by unfavorable environmental conditions, not internal factors.

Raceme - an indeterminate inflorescence with only one order of branching. Pedicels of  flowers are about the same length.

Receptacle - the base of the flower; point of attachment of other flower parts.

Reflexed - curved backward or downward

Refractometer - device for measuring the soluble solids (sugar) content of fruit juice.

Rest - see dormancy.

Ringing - see girdling.

Rootstock (stock, understock) - the root system, the bottom part of a grafted tree.

Runner - see stolon.

Russet - tan or brownish, coarse textured area on fruit skin. May be genetic as in ‘Bosc’ pear, or may be induced by frost, dew, or injury to the fruit skin.

Samara - A dry, indehiscent, winged fruit.

Scaffold(s) - large, permanent, lateral limb(s) of a fruit tree which produce fruiting wood.

Schizocarp - A dry, dehiscent fruit from a compound ovary; fruit splits into one-seeded segments at maturity, but carpels do not dehisce to release seeds.

Scion - the above-ground portion of a plant propagated by graftage.

Scoring - making knife cuts around the circumference of a stem or branch to impede phloem transport. Similar to girdling, but without removal of a strip of bark.

Seed - A mature ovule. Contains the embryo, endosperm (only remnants in most dicots), and the seed coat(s).

Seedling rootstock - a rootstock propagated by seed.

Self-compatible - capable of successful fertilization and seed production when pollinated with its own pollen.

Self-fruitful - capable of producing a commercial crop of fruit when self pollinated.

Self-incompatibility - incapable of successful fertilization and seed production when pollinated with its own pollen. Not the same as self-sterile; some seed (and thus fruit) will be set in most self-incompatible species when self-pollinated.

Self-pollination - Pollen transfer from the anther to the stigma within the same flower or plant genotype.

Self-sterile - Lacking either pollen or eggs which are viable; cannot produce any viable seed when self-pollinated. Contrast self-incompatible.

Self-unfruitful - Incapable of setting commercial crops of fruit when self-pollinated.

Sepal - One unit of the calyx. A unit of the outermost whorl of appendages in a flower.

Septicidal capsule -  a dry, dehiscent, one- to many-seeded fruit from a single, compound ovary, opening along the septa.

Septum (pl. septa) - the partition separating the locules of a compound ovary.

Sessile - a leaf, flower or fruit attached directly to the plant with no stalk or stem.

Shelling percentage (syn. percent kernel) - the percentage of a nut’s weight contributed by the kernel.

Shrub - several-stemmed woody plant; renewal growth from the base or crown.

Silicle - A dry, dehiscent fruit from a 2-carpellate ovary, less than twice as long as wide, the carpels separated by a thin, translucent septum (replum). Common in the Brassicaceae.

Silique - A dry, dehiscent fruit from a 2-carpellate ovary, more than twice as long as wide, the carpels separated by a thin, translucent septum (replum). Common in the Brassicaceae.

Simple - undivided, as in a leaf blade or ovary, or containing only one type of structure, such as a simple bud containing only flowers or vegetative shoots.

Small fruits - a group of taxonomically diverse fruit crops, generally shrubs, herbs or vines, that produce small, soft fruit. Includes grapes, blueberries, brambles, strawberries, currants, gooseberries, and several others.

Solitary - occurring by itself, not in a cluster (as with flowers).

Spadix - A spike with a thickened and/or fleshy rachis, and generally numerous, small flowers.

Spathe - A conspicuous, protective or showy bract subtending or enclosing an inflorescence. Commonly associated with a spadix or compound spadix (as in palms).

Spike - an indeterminate, elongated, unbranched inflorescence. Flowers lack pedicels (pineapple).

Spindlebush - a type of central leader training system with numerous, shortened scaffolds arising along the leader.

Sport - a mutant strain of a cultivar (see strain).

Spur - a short, slow-growing, lateral branch generally bearing flower buds.

Stamen - The male reproductive organ of a flower; composed of the filament (stalk) and the anther (apical portion).

Staminate - said of a flower or plant which produces only male reproductive structures.

Stenospermocarpy - Seedless fruit development as a result of fertilization followed by seed abortion.

Stigma (stigmatic surface) - The terminal portion of the style, often swollen, flatten, domed, or feathery. Functions in catching pollen and allowing for its germination.

Stion - a tree propagated by graftage; STock + scION. Shorthand designation:  scion/stock; i.e., 'Granny Smith'/M.9 designates a stion composed of the scion cultivar 'Granny Smith' on M.9 rootstock. 'Granny Smith'/M.9/MM.111 designates a stion composed of the scion cultivar 'Granny Smith' with an M.9 interstock and MM.111 rootstock.

Stipules - a pair of generally inconspicuous appendages at the base of the petiole.

Stolon (syn. runner) - a horizontal, creeping stem that roots at the node or tip, producing a new plant.

Stock - abbreviation for rootstock.

Stone fruits - a group of fruit crops belonging to the genus Prunus, which have the fruit type of drupe. (Peach, plum, cherries, apricots).

Strain - a sub-subspecies of a plant; a form. A variant of a cultivar that is nearly identical, not deserving full cultivar status.

Stratification (chilling) - exposure of seed to cool (40 to 50°F) temperatures in the presence of moisture for 30 to 180 days to break seed dormancy and induce uniform germination and seedling development.

Strig - term applied to clusters of fruit in currants and gooseberries.

Style - The part of the pistil between the stigma to the ovary; often slender, elongated.

Sucker (suckering) - shoots arising from the rootstock adventitiously, either from roots or the trunk; undesirable usually, except when occurring on stock plants used for propagation.

Suffrutescent - a shrub that is slightly woody at the base, but mostly composed of herbaceous stems.

Summer pruning - pruning during the growing season.

Superior ovary - hypogynous; see ovary.

Suture - the cleft or line between the base and tip of a stone fruit.

Synchronous protogyny - when all open flowers on the same plant or cultivar have functional female, but not male parts, and later become functionally male. A perfect flower condition that favors outcrossing (Avocado).

Syconium - a fleshy, multiple fruit composed mostly of an inverted, hollow receptacle containing many individual flowers. Access to flowers is provided by a small hole or ostiole (syn. eye) at the fruit tip. Example - Fig, where the true fruits are drupelets (a multiple of drupelets, or a syncarp).

Syncarp (syn. Syncarpium) - a multiple fruit composed of many fruitlets plus a fleshy inflorescence axis. Example = mulberry.

Temperate zone - geographic region between 30 and 50° latitude having distinct seasons.

Tendril  - A slender, elongated, twining organ used for climbing in vines.

Testa - the seed coat.

Thinning - partial removal of flowers or fruitlets to increase the ultimate size of the remaining fruits. Accomplished by chemicals, mechanically, or by hand.

Thinning out (thinning cut) - removal of a limb or stem at its base; no portion of the stem remains.

Topworking - replacement of the original scion with a different one by grafting onto an established tree.

Training - obtaining a particular form for a tree or shrub by pruning, tying, bending, or staking limbs in various orientations.

Training system - a particular tree or shrub form.

Tree - large woody plant, usually with a main stem or trunk. Renewal growth generally from the top of the canopy, not the trunk or ground.

Trioecious - bearing male, female, and perfect flowers on separate plants.

Umbel - an indeterminate inflorescence where flowers are born in a plane or slight arc, resembling an umbrella. The pedicels of all flowers originate at the same place on the main axis.

Union - the point where the graft was made in a 2-part tree.

Unisexual - having only one sex, as in an imperfect flower.

Understock - another term for rootstock.

Urceolate - urn-shaped.

Utricle - A small, dry, one-seeded, indehiscent fruit with a thin, bladder-like wall. (Example - spinach).

Variety - a sub-species, or cultivar of a plant.

Vegetative bud - a bud producing leaves and stems initially; not flowers.

Vegetative propagation - producing a plant asexually, through cuttings, layers, grafting or budding, or tissue culture; NOT by sexual seed. However, apomictic seed can be considered a form of this. Results in plants genetically identical to the parent.

Vine - a plant which is not self-supporting; climbing by means of twining stems or tendrils.

Vineyard - a regular, geometric planting of grape vines.

Viticulture - the study of grape cultivation.

Water sprout - a vigorous, upright, generally vegetative shoot arising from a scaffold or main tree trunk.

Whip - an unbranched nursery tree; scion is a single shoot.

Xenia - effects of the pollen source on the tissues within the seed.

Xylem - the water conducting tissue of plants. The wood of trees, shrubs, and vines.

Yield efficiency - a measure of fruit production efficiency, using units of weight of fruit per unit of plant size: kg fruit per cm² of trunk cross-sectional area, or kg per m³ canopy volume.

Zygote - The diploid cell formed by fusion of the egg with one generative nuclei; the progenitor of the embryo within the seed.