Abiotic - nonliving.

Acclimate - to adapt to new environmental conditions.

Acidity - quality of being sour; degree of sourness; having a pH of less than 7.

Adventitious - plant parts, such as shoots and roots, produced in an unusual position on a plant or at an unusual time of development.

Aeration - to be exposed to air; to cause air to circulate through a medium.

Aggregates - (soil); clumps or cemented units of mineral and organic matter.

Algae - aquatic plants that lack a vascular system. Some are microscopic and others are large. Examples are pond scum, kelp and red tides.

Alkalinity - having a pH greater than 7.

Alternate host - a secondary host that becomes infected and is necessary for alternating generations of a disease-causing organism.

Amendment - an alteration or addition to soil to correct a problem.

Annuals - plants that complete their life cycle in a year or less.

Anther - the upper part of the stamen where the pollen is produced.

Apical bud - a bud at the apex or terminal position on a plant or branch.

Arboretum - pl. arboreta; a place where trees, shrubs, vines and herbaceous plants are cultivated for scientific and educational purposes.

Asexual propagation - the duplication of a plant from a cell, tissue or organ of the plant.

Band fertilize - to apply fertilizer in a narrow line along a row of plants or in a circle around individual plants.

Bare root - a plant that is sold or shipped dormant with no soil surrounding its roots.

Biennials - plants that complete their life cycle in two years or growing seasons.

Binomial nomenclature - a system in which the scientific name of a plant consists of two parts indicating the genus and species.

Biological control - the use of living organisms or their products to control pest populations.

Bolt - the tendency of cool-season plants to grow rapidly and produce seeds when exposed to warm temperatures.

Bonsai - a potted plant dwarfed by special cultural practices.

Bract - a modified leaf, usually reduced in size or scale-like. Sometimes large and brightly colored.

Bramble - any shrub with thorns in the rose family; usually refers to blackberries and raspberries.

Branch crown - plant tissue that is the junction of the roots and stem that forms on the side of a strawberry plant. These only form foliage.

Broad spectrum - pesticides that affect a wide variety of pests.

Bud scales - specialized tissue that covers the terminal bud and embryonic leaves of a plant during winter.

Bud union - the location of a graft.

Bulb - an underground storage organ made up of enlarged and fleshy leaf bases and a bud.

Bulbil - a small bulb that forms along the stems of certain plants, such as tiger lilies and bladder ferns.

Bulblet - a small bulb that develops around a parent bulb and can be removed to propagate additional plants.

Button - the small heads of broccoli or cabbage that form as a result of seedlings being exposed to freezing temperatures.

Cage - an enclosure used to support a plant.

Callus - wound tissue.

Cambium - the tissue in a plant that produces new cells.

Candle - the new shoot growth on needled evergreens before the needles expand.

Cane - a one-year-old shoot on a grapevine.

Canopy - the top layer of a tree including branches and foliage.

Capillary action - a force that causes liquids to rise or fall when inside very small tubular spaces.

Carbon dioxide, CO2 , - a colorless, odorless gas found in the air. It is absorbed by plants and exhaled by animals.

Cell - the unit of plants that makes up tissues. Cells have a cell wall that encloses the protoplasm.

Chlorophyll - green pigments in plants that facilitate photosynthesis.

Cloche - a transparent plant cover used to protect plants from cold temperatures.

Cold composting - composting under conditions where the temperatures do not rise to 140o F.

Cold frame - a glass-covered frame without artificial heat used to protect plants and seedlings.

Collar - a band of material used as a mechanical barrier to protect a plant from damage by insects.

Compaction - a state where soil particles are forced closely together, reducing pore space.

Compost tea - a low-nutrient liquid that results from placing plant debris in water and allowing it to decompose.

Composted manure - animal feces that have been aged in a pile, allowing much of the nitrogen to leach from the feces. A nonburning organic fertilizer.

Cool-season grass - turfgrasses that actively grow during the cooler spring and fall weather. These include Kentucky bluegrass, the fescues, ryegrasses and bentgrass.

Cordon - horizontal branches of a grapevine trained along the trellis; also called the arms. The canes left after pruning which will produce fruiting shoots and new canes.

Core aeration - increasing air penetration of the soil by removing plugs of soil. A heavy machine with hollow prongs is moved across a lawn pushing the prongs into the soil and pulling out plugs of soil.

Corm - a short, thickened, underground, upright stem in which food is stored.

Cormel - a small corm that forms around the parent corm. It can be removed and planted to propagate a new plant.

Cotyledon - the leaf or leaves of the embryo, also called seed leaves.

Cross-pollination - the transfer of pollen from one plant to the stigma of another plant.

Crotch - the angle measured from the trunk of a tree to the upper surface of a branch.

Crown - the part of a plant where the root and the stem meet.

Cultivar - also cultivated variety; a subdivision of a species, a result of human-manipulated hybridization.

Cultivation - preparation of the soil for growing plants.

Cultural control - the use of good gardening techniques to control pest populations.

Cuticle - a waxy or varnish-like layer covering the outer surface of leaves.

Cutin - the waxy or varnish-like material that makes up the cuticle.

Day-neutral plant - a plant that will flower under any day length.

Days to maturity - the number of days between planting the seed and first harvest.

Deadhead - to remove spent blossoms of herbaceous plants.

Deciduous - plants that drop their leaves at the end of each growing season.

Dehydration - an abnormal loss of fluids.

Desiccation - drying.

Diameter breast high - the diameter of a tree trunk at a height of 4-1/2 feet above the ground.

Dicot - also dicotyledon; flowering plants with embryos that have two cotyledons.

Dioecious - plants that have only male or only female flowers on an individual plant.

Disease resistance - the tendency not to be infected by a particular pathogen.

Disease tolerance - the ability of a plant to continue growing without severe symptoms despite being infected by a pathogen.

Division - a method of propagation by separating and planting segments capable of growing roots and shoots.

Dormancy - a state of suspended growth or lack of visible activity caused by environmental or internal factors.

Double dig - a method of digging a garden bed which involves removing the soil to the depth of one spade blade and then digging down an equal distance, breaking up and mixing the soil.

Drip irrigation - a system of tubes with small holes that allow water to drip out onto the root zone of plants. A water-conserving irrigation system.

Drip line - a line encircling a tree corresponding to the furthest extension of the branches of a tree.

Drought - a prolonged period of dryness that can cause damage to plants.

Endophyte - a plant living within another plant. In turfgrasses, it is a fungus within the grass plant secreting substances that repel insect pests.

Epiphyte - A plant that usually grows on another plant and gets its nutrients from the air and water.

Espalier - a plant trained to grow flat against a wall or trellis.

Established - the state of a plant when it is adjusted to the site and thriving.

Evergreen plants - plants that do not drop the current season's leaves at the end of the growing season.

Fallow - cultivated land that is allowed to lie idle for a growing season.

Fertilization - the application of nutrients for plant growth. The union of the egg and sperm.

Fertilizer burn - the browning and in extreme cases, killing of plants from exposure to excessive nitrogen.

Fibrous root - a root system where the roots are finely divided.

Field capacity - the amount of water soil can hold against the force of gravity.

Filament - the part of the stamen that holds the anther in position for pollen dispersal.

Force - manipulation of environmental factors to make a plant blossom out of season.

Frond - the leaf of a fern.

Fruiting wood - on grapevine, the one-year-old canes that will produce the current year's fruit.

Fungi - saprophytic and parasitic organisms that lack chlorophyll and include molds, rusts, mildews, smuts, mushrooms and yeast; singular, fungus.

Genus - groups of closely related species clearly defined from other plants.

Girdling - removing the bark from a woody stem to kill the plant. Encircling a stem with a material so that the cambium layer is destroyed, killing the plant.

Grafting - the joining of two separate structures, such as a root and a stem or two stems, so that by tissue regeneration they form a union and grow as one plant.

Green manure - an annual cover crop that is turned into the soil before it flowers.

Greensand - an organic source of potassium. About 7% potash plus 32 trace elements.

Guard cells - specialized crescent-shaped cells that control the opening and closing of a stomata.

Harden off - to acclimate a plant to harsher conditions.

Hardiness - the ability to withstand harsh environmental conditions.

Hardwood cutting - a mature, woody piece of a woody plant that is removed to asexually propagate a new individual plant.

Heeling in - covering the roots of dormant plants with soil or mulch for short periods.

Herbaceous - a non-woody plant.

Hill planting - grouping plants in a cluster, not necessarily on an elevated mound.

Holdfast - a part of a plant that clings to a flat surface.

Hotbed - a bed of soil enclosed by a structure with a top of glass, heated, often by manure, for forcing or raising seedlings.

Humidity - the amount of moisture in the air.

Humus - brown or black, partially decomposed plant or animal material that forms the organic portion of soil.

Hybrid - a first generation cross between two genetically diverse parents.

Inoculant - a microorganism which is introduced into the soil to improve growth of legume plants.

Inorganic - being or composed of matter other than plant and animal; often of mineral origin.

Internode - the area on a stem between nodes.

Interstem - an intermediate stem piece that is grafted between the scion and the stock.

Irrigation - to supply water by artificial means, such as with sprinklers.

Landscape fabric - a loosely intertwined fabric that is placed over the soil as a mulch to reduce weed invasion.

Latent bud - a dormant bud that is capable of growth and development.

Lateral bud - smaller buds on the sides of stems, responsible for growth of leaves and side branches.

Lath house - a structure consisting of a frame supporting strips of wood which are spaced to provide about 50% shade.

Layering - a method of propagation in which adventitious roots form before the new plant is severed from the parent plant.

Leach - to dissolve in water and wash away.

Leaf scorch - injury to leaves due to lack of sufficient water, excessive transpiration or injury to the water-conducting system of the plant.

Long-day plant - a plant that requires a night shorter than its critical dark period, usually 12 hours or less, to develop flowers.

Macronutrients - the nutrients needed in large amounts by plants: nitrogen, phosphorous, potassium, magnesium, calcium and sulfur.

Marginally hardy - close to the limit of hardiness that a plant can withstand. Planting plants that are marginally hardy is risky, because under the most severe conditions for that zone, the plant may not survive without extra protection.

Matted-row - a system of planting where plants are placed off center or are centered on a diagonal.

Meristem - a region of cell and tissue initiation; cells that do not mature, but remain capable of further growth and division.

Microclimate - the local climate of a small site or habitat.

Micronutrients - the nutrients needed in small amounts by plants: iron, manganese, zinc, copper, molybdenum, boron and chlorine.

Monocot - or monocotyledon, flowering plants that have embryos with only one cotyledon.

Monoecious - plants that have both male and female flowers on the same plant.

Moss - small, leafy plants that do not produce flowers or seeds. They grow in moist, shaded areas where fertility is low.

Natural - occurring in nature.

Node - the location on a stem where buds form.

Nodules - swellings on the roots of legumes where nitrogen-fixing bacteria live.

Nutrients - substances a plant takes in and uses as food for growth and development.

Organic - of plant or animal origin.

Ovary - the swollen bottom part of the pistil that contains the ovules or immature seeds.

Oxygen, O2, - a colorless, tasteless, odorless gas that is 1/5 of the volume of the atmosphere.

Parasitic - an organism that lives on or in another living organism (the host) and obtains nutrition from the host.

Perennials - plants that do not die after flowering, but live from year to year.

Petals - a whorl of structures that surround the inner reproductive organs of a flower. Together they are called the corolla. They often attract insects by color or nectar, facilitating pollination.

Phloem - the part of the vascular system that moves food through the plant.

Photoperiodism - responses of plants to the relative lengths of light and dark cycles.

Photosynthesis - the production of sugar from carbon dioxide and water in the presence of chlorophyll, activated by light energy and releasing oxygen.

Phototropism - the bending of a plant toward the direction of more intense light.

Pinch - breaking off the terminal growing point of a plant to encourage axillary buds to grow.

Pistil - the female part of the flower, consisting of one or more carpels and enclosed ovules.

Pollard - a tree cut back to the trunk to make a dense cluster of branches and foliage.

Pollen - the microspores that carry the male gametophyte of seed plants.

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

Potting medium - material used for growing plants in containers. Mixes may include vermiculite, perlite, sand, peat, charcoal, loam and fertilizer.

Procumbent - having stems that trail along the surface.

Propagation - to increase the number of plants by sexual or asexual means

Prune - to cut back parts of plants for better shape, disease control or improved fruiting.

Raised bed - a gardening area where the soil has been elevated above ground level. This gardening technique is especially used where soil drainage is poor. Beds can be raised in a structure of wood, brick, cement blocks, etc.

Renovation - removing an old planting and putting in a new one or removing and replacing only part of a planting. In strawberry culture, this process involves removing the leaves of the plants and cultivating the aisle to reduce the width of the row of plants to no more than 15 inches.

Respiration - the process where food is oxidized (burned) to release energy.

Rhizome - an underground, horizontal stem.

Root - the portion of the plant usually found below ground. They are distinguished from stems by not having nodes.

Root girdling - encircling roots at or below the surface of the ground that tend to strangle the plant.

Root hairs - tubular outgrowths of surface cells of the root.

Root prune - to cut back the roots of a plant to encourage them to develop more fibrous roots or to reduce the mass of roots. Usually done before transplanting established plants or repotting houseplants.

Rootstock - the root onto which a scion or bud is grafted or budded.

Row cover fabric - a loosely woven translucent fabric used to keep insect pests off crops. It also functions as a cloche.

Scarification - the physical or chemical treatment given to some seeds in order to weaken the seed coat sufficiently for germination to occur.

Scion - the upper part of the union of a graft.

Scorch - injury to leaves due to lack of sufficient water, excessive transpiration or injury to the water-conducting system of the plant.

Seed - the organ that forms after fertilization occurs.

Self-cleaning - herbaceous plants that drop spent blossoms, thus not requiring deadheading.

Sepals - structures that usually form the outermost whorl of a flower. Together, they are called the calyx.

Sexual reproduction - production of new generations involving the exchange of chromosomes from both a male and female parent.

Sharp sand - a coarse sand used in building.

Short-day plant - a plant that requires a night longer than its critical dark period, usually 12 hours or more, to develop flowers.

Side-dress - to apply fertilizer to the side of a row of growing plants or around single plants.

Softwood cutting - a non-woody piece of a woody plant that is cut from the stock plant to asexually propagate a new individual plant.

Soil conditioner - any material added to soil to improve its structure, texture, tilth or drainage.

Soilless mix - potting medium that contain a mixture of ingredients from the materials listed for potting medium, but no mineral soil.

Soluble salt - salts from fertilizers and tap water that are dissolved in water.

Solvent - a liquid that can dissolve a substance.

Species - a group of closely related individuals that have the potential to reproduce with each other; a unit of classification.

Specific epithet - the second name of the binomial given to a species; for instance, "rubrum" is the species epithet of Acer rubrum.

Spines - a sharp-pointed woody structure, usually a modified leaf or leaf part.

Spore - a minute reproductive body produced by primitive organisms, such as ferns and fungi.

Stake - a piece of pointed wood or metal that is driven into the ground to support a plant.

Stamen - the male part of the flower. It consists of the anther and the slender filament that holds it in position.

Stem - the main trunk of a plant. It develops buds and shoots.

Stigma - the part of the pistil that receives the pollen grains; usually the top of the pistil.

Stock plant - a plant used as a source for cuttings.

Stomata - an opening or pore in leaves that is surrounded by guard cells.

Stratification - storing of seeds at low temperatures under moist conditions in order to break dormancy.

Style - the slender part of a pistil between the stigma and the ovary.

Succession planting - planting portions of a crop over a period of time to get a continuous harvest over a long period of time.

Succulent - having tender, new growth or thick, fleshy tissues which store water, such as cactus.

Sucker - a shoot arising from the root or lower part of the stem of a plant.

Sunscald - plant injury caused by exposure to bright sunlight, excessive heat and/or wind.

Symptom - evidence of disease or damage.

Synthetic - substances produced by chemical or biochemical means.

Taproot - a stout, tapering primary root that has limited side branching or fine roots.

Temperate - moderate; the zones between the tropics and the polar regions of the earth.

Tendril - a slender, coiling modified leaf or leaf part. These help plants climb.

Tepee - a tripod of stakes used to support climbing plants.

Terminal bud - large, vigorous buds at the tips of stems.

Terrace - a series of flat platforms of soil on the side of a hill, rising one above the other.

Topiary - training, cutting and trimming of plants into ornamental shapes.

Topsoil - uppermost layer of soil, usually darker and richer than the subsoil.

Toxicity - intensity of a poison.

Transpiration - the loss of water from plant tissues in the form of vapor.

Transplanting - digging up a growing plant from one location to plant it in another location.

Trellis - a frame of latticework used as a support for climbing plants.

Tropical - regions of the earth lying between the Tropic of Cancer and the Tropic of Capricorn extending around the equator where the temperature and humidity are high.

Trunk - the main stem of a tree, shrub or vine.

Tuber - an enlarged, underground stem that stores food.

Turgid - the condition of a cell, tissue or plant when it is filled with water so that it is firm; not wilted.

Understock - the part of a plant to which a graft is attached.

Variegated - plant parts having different pigments resulting in more than one distinct color or shade on the foliage.

Variety - a subdivision of a species; occurs through natural hybridization.

Vascular system - the tissue in a plant that moves fluids through the plant.

Vegetative - plant parts and processes concerning growth and nutrition and not reproduction.

Venation - the pattern of veins.

Viable - capable of growing or developing.

Whip - a very young tree that still has a flexible trunk.

Wilting point - the amount of water in a soil when a plant cannot obtain enough water to remain turgid.

Witches'-broom - a dense, bushy growth of branches and foliage caused by a parasitic fungus and mites or poor pruning techniques.

Xylem - the part of the vascular system that moves water and minerals through the plant.