Abdomen – the posterior section of the arthropod body.
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.
Allelopathy – a biological phenomenon that is characteristic of some plants, algae, bacteria, coral and fungi by which they produce certain biochemicals that influence the growth and development of other organisms. The biochemicals, called allelochemicals can have a beneficial or detrimental effect on neighbouring organisms.
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.
Anaerobic – able to live and grow where there is no air.
Annual – plants that complete their life cycle in a year or less.
Anther – the upper part of the stamen where the pollen is produced.
Anthracnose – A fungal disease of plants, usually made worse by very wet conditions like a very rainy springtime. It can cause a range of damage from spots on foliage to complete defoliation. If the plant is heavily affected, be sure it has adequate nutrients to help it renew the leaves it has lost. Rake all debris from the plant and dispose of it to prevent re-infection.
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.
Arthropod – invertebrate animals (insects, arachnids and crustaceans) that have a jointed body and limbs and usually a hard shell or exoskeleton that is molted periodically.
Asexual propagation – the duplication of a plant from a cell, tissue or organ of the plant.
Bacteria – microscopic organisms having round, rod-like, spiral or filamentous single-celled or noncellular bodies often gathered into colonies.
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.
Basal bud – A bump of growth tissue that forms in the crown of a plant.
Basal foliage – The leaves that grow around the crown of a plant.
Beneficial insects – insects that prey on or parasitize pests.
Bentgrass – a high-maintenance grass used on putting greens. It requires frequent cutting with a reel mower, frequent fertilization and watering. It is highly susceptible to several diseases.
Biennial – 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.
Biological diversity – presence of many different types of living organisms.
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.
Botrytis – A necrotic fungus made worse by humid or wet conditions. It is particularly a problem on grapes, strawberries and bulbs, but can occur on many plants. Any steps which improve air circulation and the drying of the foliage, such as thinning and elevating the plant above the surrounding soil, will help to solve the problem.
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 long straight woody stem, usually erupting from the crown of the plant, a one-year-old shoot on a grapevine.
Canopy – 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.
Carnivore – a flesh-eating animal.
Caterpillar – worm-like larva of various insects, especially butterflies and moths.
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.
Complete metamorphosis – changes in body form of insects that include egg, larva, pupa and adult; also known as complex metamorphosis.
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.
Contact insecticide – a poison that must contact the body of the insect to be controlled.
Contractile – drawing together resulting in decreased size or bulk.
Cool-season crop – a crop that grows best during the cool temperatures of spring and fall.
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.
Cover crop – a crop that improves the soil in which it is grown.
Crop rotation – growing crops of a specific family in different areas of the garden each year to avoid soil-borne diseases and nutrient depletion.
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.
Cruciferous – Vegetables of the family Brassicaceae (also called Cruciferae) are called Cruciferous vegetables; widely cultivated, with many genera, species, and cultivars being raised for food production. The family takes its alternate name (Cruciferae, New Latin for “cross-bearing”) from the shape of their flowers, whose four petals resemble a cross.
Culinary – used in cooking.
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.
Cucurbit – The plant family Cucurbitace, also known as gourd family, which includes crops like cucumbers, squashes (including pumpkins), luffas, and melons (including watermelons). The family is predominantly distributed around the tropics, where those with edible fruits were amongst the earliest cultivated plants in both the Old and New Worlds
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.
Damping Off – Damping-off is a fungal disease that can kill seedlings overnight. The fungus rots the stems at the soil surface, causing the seedlings to fall over and die. A way to control this problem is with improved circulation.
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 the spent flowers to promote further blooming, and improve the plant’s appearance. A general term. Pinching, shearing, cutting back to a flower bud and stem cutting are all methods of deadheading.
Deadleaf – To remove damaged foliage from a plant.
Deciduous – plants that drop their leaves at the end of each growing season.
Dehydration – an abnormal loss of fluids.
Desiccation – drying.
Determinate – growth that is limited.
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.
Drift – when a pesticide is blown by wind onto nontarget organisms.
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.