annual : a plant that completes its life cycle (from seed to seed) within a single growing season. A spring annual is a plant that is grown in the ground in late winter, is planted in the spring and then completes its life cycle by midsummer

basal : growing at the base or bottom of a plant

berry : a type of fruit with seeds contained in or about the pulp or flesh

biennial : any plant needing two seasons of growth (with a dormant period between growth stages) to complete its life cycle, from seed to seed. In the first year, plants form vegetative growth, and in the second year they flower

bract : a modified leaf that may occur at the base of a flower or stalk. In the dogwood, white or pink bracts surround the flowers, giving the casual viewer the impression that these leaves are petals

broadleaf : having broad and flat leaves that persist from year to year

calyx : the group of sepals, or outer floral leaves, of a flower

catkin : a dry and scaly flowering spike

chlorosis : a symptom of disease or disorder in plants in which a plant or part of a plant is light green or greenish-yellow because of poor chlorophyll development or destruction of chlorophyll

corymb : a flat or convex cluster of flowers in which the flowers lie as a dome or dish

crest : an elevated ridge on a surface, such as the ridges on a flower petal

cultivar : a cultivated variety or strain of a plant produced by horticultural techniques and not normally found in wild populations; a cultivar name is written after the Latin name, usually marked by single quotation marks, as in Zinnia elegans ‘Tom Thumb’

culture : a small segment of a plant grown in a nutrient-rich medium; asexual reproduction

deciduous : shedding foliage each year, as applied to trees and shrubs; losing fruit or leaves at maturity or at the end of the growing season; not evergreen

dioecious : having a type of sex expression in which plants produce male and female flowers on separate plants

drupe : a type of fruit with a fleshy outer layer and a hard, nutlike core, such as peaches or cherries

evergreen : having persistent leaves with a crown that is never wholly bare, as applied to a tree or shrub

exfoliate : to peel away in thin layers

family : in the Linnaean classification scheme, a category between order and genus that is a group of closely related genera or (rarely) a single genus; an onion is scientifically considered in the genus Allium, of the family Liliaceae, in the order Liliales

genus : in the Linnaean classification scheme, a category between family and species that is a group of similar organisms; a genus consists of one or more species. An elm may be scientifically known as a member of the genus Ulmus and the family Ulmaceae

habit : the overall appearance of a plant

herbaceous : not woody; referring to plants whose tops are killed back by frost but whose roots and crowns remain alive and send out top growth when favorable growing conditions return

hybrid : the product of a cross between two genetically different parents

monoecious : having a type of sex expression in which plants produce male and female structures on the same plant

native : indigenous or occurring naturally in a given geographic locale and therefore not introduced by humans either accidentally or intentionally

naturalize : to encourage a plant to grow and spread in an area as if it were native, that is, so that the plant then maintains itself without further human intervention

panicle : a loosely branched, pyramidal cluster of flowers

perennial : a plant that normally lives more than two growing seasons and, after an initial period, produces flowers annually

pH : the reciprocal of the hydrogen ion concentration of a medium. A value on a scale of 0 to14 gives a measure of the acidity or alkalinity of a medium; pH values of 0 to 6.5 indicate acidic conditions, a pH value of 7.0 is neutral and pH values greater than 7.0 are alkaline

pome : a type of fruit with flesh derived from an enlarged receptacle growing around an ovary; apples and pears are examples of pomes

propagate : to increase numbers of or perpetuate a species by sexual (seed) or asexual reproduction

prostrate : lying flat on the ground

raceme : a stalk that continues to grow and on which flowers are borne on individual stems; the lily-of-the-valley features racemes of white flowers

reflexed : bent or curved backward

rhizome : a creeping underground stem, usually horizontal, that produces roots and leaves at the nodes

rosette : a plant growth habit whereby leaves radiate from the crown or center of the stem with very short internodes; many biennials exhibit rosette-type growth in their first year

samara : a dry, winged fruit consisting of a single seed, as of maple and ash

sepal : an individual leaf that is part of the outer floral leaves, usually greenish

species : the basic unit of Linnaean classification; a taxonomic subdivision of genus represented by plants that can freely interbreed but rarely with other species. In the Latin name Ulmus americana, the genus is Ulmus and the species epithet is americana; together Ulmus americana constitutes the species

spike : stalkless flowers occurring singly or in clusters

stamen : the male reproductive structure of a flower consisting of the anther (pollen producer) and a slender filament

stolon : a stem that grows horizontally above the ground and may produce roots and shoots at the nodes (e.g., a runner)

sucker : a rapidly growing shoot developing from an underground root or stem

terminal : at the tip or end

trade name : an arbitrary name created by a nursery or other organization to distinguish its product from all others and to protect it legally from misuse

woody plant : any plant that creates branches and stems that do not die in the winter

zone : a region that differs significantly by climate and temperature range from all adjacent areas