ACCENT PLANT: A plant that is the focal point. A plant intended to stand out from other plants and draw the viewers attention.
ACID MEDIUM: A compost which contains little or no lime and has a pH of less than 6.5. Sometimes referred to as "sour" soil by gardeners.
ACID RAIN: Rainwater that contains sulphur dioxide and other pollutants.
ACID SOIL: A soil with a pH lower than 7.0 is an acid soil. (a soil pH higher than 7.0 is alkaline) Basically, pH is a measure of the amount of lime (calcium) contained in your soil.
ACRE: A measure of land totaling 43,560 square feet. A square acre is 208.75 feet on each side.
ADVENTITIOUS: Having growth from places where normally growth does not occur.
ADVENTITIOUS PLANT: A young plant that develops in an asexual manner on the leaves or stems of the mother plant.
AERATION: Loosening or digging the soil to increase air and water penetration.
AERIAL ROOT: A root which grows out from the stem above ground level.
AEROBIC: Usually used for describing a characteristic of compost heaps. Describes organisms living or occurring only in the presence of oxygen.
AGGREGATE CULTURE: The use of solid material to grow plants. Some examples are: gravel, rockwool, sand, all with the additional use of a nutrient water soluble solution.
AGRICULTURAL EXTENSION SERVICE: A county agency that is supported and monitored by the land grant university for each individual state.
AIR LAYERING: A specialized method of plant propagation accomplished by cutting into the bark of the plant to induce new roots to form.
ALKALINE SOIL: Soil that has a pH level of about 7.0 or more. Sometimes referred to as "sweet" soil by gardeners or farmers.
ALL AMERICAN ROSE SELECTIONS, INC (ARRS): This is made up of roses that have been on trial for two years in official test gardens throughout the US. The association is comprised of rose producers, growers, and people who introduce new hybrids.
ALL AMERICA SELECTIONS (AAS): This is a group of people in the horticultural business who test new cultivars of flowers and vegetables. All of these gold medal winners can be raised from seed.
ALPINE: Plants from high mountain regions. Anything that is from above the tree line. They are able to overwinter beneath deep snow protected from extreme low temperature by their moisture.
ALPINE HOUSE: A special greenhouse created to meet the requirements of alpines. It is usually kept cool in the summer by shading the glass. In the winter it is unheated unless it needs to provide protection from very severe cold.
ALTERNATE: Leaf form, where the leaves are arranged singly at different heights on the stem. Compare opposite and whorled.
AMENDMENT: Adding additional ingredients to the soil. Usually they are described as soil amendments. Leaf mold, compost, peat moss, and sand can all be used as soil amendments.
ANAEROBIC: Describes organisms living or occurring when oxygen is absent. Usually term used when talking about compost heaps.
ANNUAL: A plant which completes its life cycle within one year of germination. See also biennial and perennial.
ANTHER: The part of the flower which produces pollen. It is the upper section of the stamen.
APHIDS: Small sap sucking insects. They infect foliage and are easily recognized by the sugary "honey dew" that they secrete that often attracts ants.
APICAL: At the tip of a branch.
AQUATIC PLANTS: Plants which grow in, live in, or live on the water.
ARBOR: A structure used in the garden to support vines of all sorts for a walkway or just a focal point. A grape arbor, for example.
ARBORETUM: A garden with a large collection of trees and shrubs cultivated for scientific or educational purposes.
AREOLE: A small well-defined area, usually hairy and cushion-like, found on the stem of cacti.
ASEXUAL: Vegetative reproductions - i.e. cuttings and division.
ATRIUM: A structure that provides lots of above light for plants. Commercial buildings often have their foyer as an atrium. Many homes have built in atriums.
AUXIN: A hormone that controls plant growth.
AWL-SHAPED: A narrow leaf which tapers to a stiff point.
AXIL: Axillary bud occurrs in the axil or angle of leaf and stem; and axillary shoot which grows from the axil or angle of leaf and stem