Glossary: N-Z

N O P Q R S T U V W X Y Z

Glossary A - M

N

Necrosis: The death of a cell, tissue, or organ while the remainder of the plant is still living.
Nematocide: A substance that kills nematodes.
Nematode: ny of the round, cylindrical, unsegmented worms of the phylum Nematoda; some cause plant diseases.
Node: A point on the stem where leaves are attached and buds arise in the axils of the leaves. Grape: The enlarged portion of a cane or shoot at which leaves, clusters, tendrils, and/or buds are located at regular intervals.
Nucleus: A specialized body within a cell that contains genetic information and is associated with the control of essential processes within the cell.

O

Obligate: An organism that can develop and survive in only one type of environment; as in obligate parasite, which is any parasite that cannot exist independently of its living host.
Offset: A short, prostrate offshoot or branch growing from the crown of a plant and having a fleshy, scaly bud or a rosette of leaves located terminally. Offsets often form roots and are used to vegetatively propagate some plants.
Offshoot: A lateral shoot that rises from the main stem of a plant; often used for vegetative propagation of some plants, e.g., date palms.
Open center system: See vase system.
Opposite buds and leaves: Arrangement in which buds and leaves occur in pairs at a node, directly across the stem from each other.
Organic: 1. Composed of or derived from plant or animal material. 2. A compound that contains carbon.
Ovary: The swollen basal portion of a pistil; the flower part containing the ovule(s) or seed.
Overcropping (grape): The production of more crop than the vine can bring to maturity at normal harvest time.
Ovule: Part of the ovary containing one female gametophyte (egg). Following fertilization, the ovule develops into the seed.

P

Palisade layer: A layer of tightly spaced, elongated cells lying under the upper epidermis of leaves. Photosynthesis is most active in these cells.
Palmate: Having the general shape of human hand with the fingers extended.
Parthenocarpic fruit: Fruit produced without fertilization.
Partially self-ferile: A heavier fruit crop is set when two or more varieties are planted nearby.
Ped: An individual, natural soil aggregate such as crumb, prism, or granule.
Pedicel (grape): The stalk of a single flower or berry.
Perennial: A woody or herbaceous plant that lives from year to year and does not die after flowering once.
Perfect flower: A flower containing both stamens and pistil; a bisexual flower.
Perlite: White and very porous volcanic mineral that is sometimes used as a medium for rooting cuttings or as a soil amendment.
Petiole: The thin stalk that attaches a leaf to the stem.
pH: The negative logarithm of the hydrogen-ion concentration of a solution; a notation to express the alkalinity or acidity of a solution, as in the solution formed when water is present in soil, on a scale from 0.0 to 14.0. A pH of 7.0 is neutral, values less than 7.0 are acid, and values greater than 7.0 are alkaline.
Pheremone: A substance that is produced and discharged by one organism and that induces a physiological response in another, such as the sexual attractants of insects.
Phloem: Vascular tissue that conducts synthesized carbohydrates in vascular plants.
Photoperiod: The length of light in a 24-hour day.
Photoperiodism: The response of some plants to the relative lengths of day and night, expressed as formation of flowers, tubers, etc.
Photosynthesis: The production of carbohydrate (sugar) from carbon dioxide and water in the presence of chlorophyll, using light energy and releasing oxygen.
Phytotoxic: Harmful or poisonous to a plant or portions of a plant; substances that are poisonous to all or certain plants.
Pinnate: The pattern of arrangement of dicot leaf veins, leaflets of compound leaves, lobes, etc., that resembles the structure of a feather in that they are arranged along the sides of a central axis (e.g., a major leaf vein, major petiole, etc.).
Pistil: The central and female part of a flower consisting of the stigma, style, and ovary, and having one or more compartments (carpels) that bear the ovule(s).
Plumule: The bud of an embryonic plant.
Pollen (grain): Tiny, grainlike structures in the anther of a stamen containing sperm nuclei that represent the male gamete in seed plants.
Pollen tube: The tube formed in the style following germination of the pollen grain.
Pollination: Transfer of pollen from the anther to the stigma of the same or another flower.
Pome: A fleshy fruit with a leathery core as produced by apple, pear, and quince.
Porosity (soil): The degree to which a soil is permeated with open spaces, cavities, or pores; expressed as a percentage of the total volume of a quantity of undisturbed soil.
Postemergent herbicide: An herbicide that is applied before weed seeds emerge or geminate.
Pot herb: Greens; any plant yielding foliage that is edible when cooked, such as spinach, kale, chard, mustard.
Predator: Any animal, including insects, that preys upon and devours other animals. Distinguished from a parasite, which lives on only one host at a time and usually does not destroy the host.
Preemergent herbicide: An herbicide that is applied before weed seeds emerge or germinate.
Primocanes: One-year old (or less) stems in blackberries and raspberries that do not bear fruit.
Prismatic (soil structure): A type of soil structure in which the aggregates that naturally form are relatively large and angular, resembling a prism.
Propagate: To generate or to multiply by sexual or asexual means.
Protoplasm: The living material of and in a cell.
Pupa: In insects with complete metamorphosis, the inactive stage between the larva and adult, usually enclosed in a protective structure.

Q

Quadrilateral cordon (grape): A vine training system with four cordons are formed. Compare with Bilateral Cordon.
Quiescent: Dormant or inactive.

R

Rachis (grape): The main part of the cluster stem.
Radicle: The basal end of an embryonic stem that grows into the primary root.
Receptacle: A part of the axis of a flower stalk that supports or surrounds the floral parts.
Replacement spur (grape): A 2-bud spur created during dormant pruning on a cane-pruned vine. The spur is used to form next year's fruiting canes.
Receptacle: Growth, tissues, or processes concerned with the growth and development of flowers and fruits as opposed to leaves stems, and roots; sexual.
Respiration: The controlled process in cells in which carbohydrate is biologically broken down (oxidized) and energy is released.
Rhizome: A specialized stem, usually horizontal in position at or just below the soil surface, distinguished from a root by the presence of nodes and internodes and sometimes buds.
Root ball: In container-grown and dug plants, the mass of roots attached to the plant.
Rootbound: When a plants roots become tangled, matted, and grow in circles. Always untangle rootbound plants when replanting them in a larger container or in the ground.
Root cap: The protective, thimble-shaped mass of cells over the root rip.
Rootstock: I n grafted plants, the rooted plant or plant part to which a scion is attached.Sometimes called “stock,” this is the root system (plant) propagated from seed (seedling) or vegetatively as common in clonal rootstocks on which various cultivars are budded or grafted. Many rootstocks are used and possess traits that relate to anchorage, size control, tolerance of light and heavy soils, “wet feet,” specific nematodes and other plants and diseases.
Runner: A thin, specialized stem that grows along the soil surface and produces adventitious roots and shoots.
Russeting: Brownish, roughened areas on the skins of fruits, tubers of potatoes, etc., resulting from abnormal production of cork tissue. May be caused by disease, insects, or injury, or may be a natural varietal characteristic.

S

Saline soil: A soil containing sufficient soluble salts to impair plant growth and development.
Sand: A group of textural classes of soil in which the particles are finer than gravel but coarser than silt, ranging in size from 2.00 to 0.5 mm in diameter. Any soil class that contains 85 percent or more sand and not more than 10 percent clay.
Sap: The liquid contents of a cell or the liquid flowing through xylem or phloem.
Saprophyte: An organism that obtains its food from the remains of dead plants or animals.
Sapwood: The outer wood of a stem or tree trunk, usually light in color and physiologically very active.
Scaffold (branches): The main branch(es) of a tree.
Scarification: The abrasion, scratching, or modification of a seed's surface to increase water absorption and break dormancy.
Scion (pronounced SI-on): A branch, bud, or shoot removed from one plant and grafted onto another plant (the stock or rootstock). A detached stem, usually dormant, used in asexual propagation by grafting techniques.
Scoring: A type of phloem disruption that consists of running a knife blade around the stem to make a narrow cut through the phloem.
Seed: Structure that is formed by seed plants following fertilization and that contains an embryonic plant and usually a food supply and protective covering; a fertilized ovule.
Seed coat: The outer covering of a seed.
Seedling rootstocks: Seedling rootstocks are propagated from seed selected from various cultivars and typically produce well anchored trees. The terms standard or standard root or standard rootstock imply that the rootstock is seedling and that the cultivar grown on that rootstock will be a full size tree.
Self-compatible (self-fruitful): Able to produce normal fruit and seed with self-pollination; sets and matures fruit without pollen from another cultivar.
Self-fertile: One variety is needed for pollination.
Self-sterile: Two varieties are needed for pollination.
Self-incompatible (self-unfruitful): Unable to produce fruit and seed when self-pollinated; requires cross-pollination from another cultivar.
Self-pollination: Transfer of pollen from the anther to the stigma of the same flower or of another flower on the same plant or within a cultivar.
Senescence: The stage in the life of a plant or plant part when its rate of metabolic activity declines prior to death.
Sepal: One segment of the calyx.
Set: A small propagative part (bulb, shoot, tuber, etc.) suitable for setting out or planting.
Sexual propagation (seed propagation): Propagation that uses the fusion of male and female gametes to develop a new individual plant.
Sexual reproduction: See sexual propagation.
Shoot: The upper part of a plant consisting of stems and leaves; a young growing branch or twig. Grape: Current season's succulent and green stem growth. It becomes a cane when over half of its length becomes woody with a tan or brown color.
Short-day plant: A plant in which the flowering period or some other process is regulated by daily exposure to light shorter than a certain maximum number of hours, usually less than 12 hours.
Sidedressing: Applying fertilizer to the soil at the side of a plant row, usually after the crop has started to grow.
Silt: 1. Small, mineral soil particles ranging from 0.05 to 0.002 mm in diameter. 2. Textural class of soils that contains 80 percent or more silt and less than 12 percent clay.
Slip: A cutting from a plant, usually softwood or herbaceous, used for propagation or grafting.
Slip (melon harvesting): See full-slip and half-slip.
Sodic soil: A soil that contains sufficient sodium to adversely affect its physical properties and water infiltration; a soil with an exchangeable sodium percentage greater than or equal to 15 percent.
Soil: The natural medium on the surface of the earth composed of minerals, organic matter, water, air, and various organisms, in which plants typically grow.
Soil amendment: A substance added to soil to alter one or more of its physical or chemical properties.
Soil horizon (profile): A layer of soil with well-defined physical and chemical characteristics produced through the soil- formation processes.
Soil moisture tension (SMT): The amount of force under which a given quantity of water is held by a soil.
Soil structure: The degree that soil particles (sand, silt, clay) naturally arrange into aggregates that vary in form and size, such as granular, platy, massive, and single-grained.
Soil texture: The relative proportions of sand, silt, and clay in a soil expressed as a percent by weight; the coarseness or fineness of a soil.
Species: A group of closely related individuals that are self-perpetuating and usually inter- cross; the basic unit of the binomial system of naming organisms, as in Liquidambar styraciflua (American sweetgum), which consists of a genus name and its specific epithet. Abbreviated sp. (sing.) or spp. (pl.).
Specific epithet: In the botanical or binomial system of identifying organisms, the descriptive term that modifies the genus in a specific name, often mistakenly called species; e.g. Liquidambar styraciflua is the species name, Liquidambar is the genus and styraciflua is the specific epithet.
Sperm: A mature male germ cell.
Spore: A minute reproductive body or cell produced by lower plants.
Sport: A sport is a mutation (genetic change), naturally occurring or induced to arise from a bud. It differs from the parent plant and can be vegetatively propagated to give rise to a new cultivar.
Spur: A short, stubby shoot primarily bearing flowers, as in some fruit trees. Grape: A short fruiting unit of one-year-old growth, usually consisting of one or two nodes; retained at pruning.
Spur pruning: A system of pruning grapes in which dormant canes are headed back to create short stubs bearing two or three buds.
Spur-type tree: A fruit tree (primarily apple and cherry) that has shortened internodes and a greater number of spurs; about two-thirds the height of standard non- spur-type trees. Spur type is used in reference to the cultivar’s habit of growth; on a given amount of wood, spur type cultivars produce more fruiting spurs than do non-spur type cultivars. Spur type is used in reference to apple trees; spur types are natural or genetic semi-dwarfs, which are smaller, more compact, and about two-thirds the size of normal apple trees when grown on standard root.
Stamen: The male part of the flower producing the pollen, usually composed of anther and filament.
Staminate: A flower that has stamens but no pistil and hence is imperfect; a plant bearing only male flowers.
Stem: An axis of a plant usually bearing leaves with buds in the axils. It may be above or below ground, and the leaves may be functional or specialized.
Stem cutting: Any part of a stem used for plant propagation by severing it from the parent plant.
Stigma: The apex of the pistil that receives pollen.
STM: See soil moisture tension.
Stock: See rootstock.
Stolon: A horizontal or trailing stem that gives rise to new shoots; a runner.
Stomate (stoma) (pl., stomata): The opening or pore, mainly in leaves, through which gases are exchanged and water vapor is lost; controlled by guard cells.
Stratification: A method of storing seeds or other reproductive structures at a temperature from 35° to 45°F (2° to 7°C) in alternate layers with (or mixed in with) moist sand, peat moss, or other medium, as a means of overcoming dormancy.
Style: The part of the pistil that connects the ovary and stigma, through which the pollen tube grows to the ovule.
Subspecies: A group of individuals within a species, distinguished by certain common geographical or varietal characters. Abbreviated ssp. (pl.).
Subtropical crop: A crop that will survive very short periods of freezing temperatures but will not survive in areas with a cold winter climate.
Succession planting: Growing two or more crops, one after the other, on the same land in one growing season.
Sucker: A rapidly-growing, upright secondary vegetative shoot that develops from the root, crown, or stem of a plant. Grape. A cane that emerges from below the bud union, and therefore comes from the rootstock rather than from the variety grafted onto it.

T

Taproot: A stout, tapering main root from which arise smaller lateral roots.
Temperate zone crop: A crop able to adapt so that it survives temperatures considerably below the freezing point.
Terminal bud: A bud that develops at the end of a stem or shoot.
Thatch: The layer of dry, dead plant material and organic matter at the soil surface, common in turfgrass.
Thinning out: Removal of an entire shoot or branch.
Tilth: The physical condition of the soil in relation to its ability to support plant growth.
Tissue: A group of organized plant cells that perform a specific function.
Topdressing: A material, such as sand or fine-textured organic matter, applied thinly to the soil or crop surface as a fertilizer, soil conditioner, or to reduce thatch.
Topping: The cutting off of the main leader of a tree.
Training: Directing the growth of a plant to a desired shape by pruning while young or fastening the stem and branches to a support.
Translocation: The movement of a substance such as water, carbohydrates, or a pesticide from one part of a plant to another.
Transpiration: The loss of water from plant tissues in the form of vapor, mainly through stomata.
Trellis (grape): A permanent vine supporting system consisting of a stake and one wire at a minimum, and at a maximum, a stake plus one or more crossarms with additional wires on an arbor system.
Tropical crop: A crop that originated in tropical areas and is usually subject to cold injury at temperatures near the freezing point.
Tuber: An enlarged, fleshy, underground stem bearing buds; usually a storage organ.
Tuberous root: An enlarged root that tapers toward both ends, as in dahlia and sweet potato; usually a storage organ.

U

Unavailable water: Water held by the soil at and below the wilting point; water held by soil so tightly that plants cannot absorb it.

V

Vacuole: The large cavity within the protoplasm of a cell containing a solution of sugars, salts, etc.
Variety: In the botanical or binomial system of identifying organisms, a naturally occurring population of individuals constituting a subdivision of a species. Although technically different, variety and cultivar are commonly synonymous. Variety and “named variety” are commonly used to mean the same as cultivar. Technically, it means a naturally occurring variant of a species.
Vascular bundle: A strandlike portion of the vascular tissue of a plant, composed of xylem and phloem, typical in monocots.
Vascular cambium: See cambium.
Vascular tissue: The tissue consisting of xylem and/or phloem that is responsible for transporting water, carbohydrates, and/or the associated soluble materials through higher plants.
Vase (open-center) system: A system of training in which the central leader is cut off 18 to 30 inches (45 to 75 cm) from the ground, and three to five side branches become the scaffolds and spread to form the framework of the tree.
Vector: An organism, usually an animal, that can transmit a pathogen.
Vegetative: Growth, tissues, or processes concerned with the growth and maintenance of the plant body; asexual; concerned with leaves, stems, roots as opposed to flowers and fruits.
Vegetative propagation: See asexual propagation.
Vein: The vascular bundle forming a part of the framework of the conducting and supporting tissue of a leaf or other plant organ.
Vernalization: The inducement or promotion of flowering by exposure to low temperature, as in some bulbs and biennial plants.
Virulence: A strong capacity to produce disease.
Volatilization: Evaporation of a substance under normal temperature and pressure ranges.

W

Warm-season crop: A crop, usually of tropical origin, that goes dormant or is injured as soon as temperatures drop slightly below freezing; crops that grow best or produce highest quality produce during the warmest season(s).
Water sprout: See sucker.
Weed: Any plant growing out of place; a plant growing where it is unwanted or interferes with more desirable plants.
Whorl: A pattern of arrangement with three or more buds, leaves, or branches, usually at a single node, each on a different plane.
Wilted: Lacking turgidity; drooping or shriveling of plant tissue usually due to a deficiency of water.
Wilting point: The stage in soil moisture depletion where a plant is unable to take additional moisture from the soil and, as a consequence, becomes wilted.
WIN (water insoluble nitrogen): In fertilizer, a source of nitrogen that is not readily soluble in water and not subject to immediate leaching.
Winter burn: Associated with desiccation. Certain atmospheric conditions (wind) along with frozen ground and/or reduced soil moisture may not meet transpirational demands—a particular problem with evergreens.
Winter injury: Low temperature injury during rest (dormancy) and affects buds, stems, main limbs, and trunk.

X

Xylem: Vascular tissue primarily responsible for transporting water and mineral nutrients from the roots to the shoots; the primary component of wood in trees.

Z

Zygote: A single cell resulting from the fertilization of an egg by a sperm and capable of developing into an embryo.

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