[ The Elmhurst College Arboretum ]

Glossary of Terms

From angiosperm to phyllotaxy, botanical terms defined.

Alternate
Referring to a phyllotaxy (see below) in which there is a only one leaf at each stem node.

Angiosperm
An “enclosed seed” plant. Only angiosperms bear true flowers or fruit. Cf. Gymnosperm.

Anthesis
The stage of plant’s life cycle when a plant’s flowers are fully open and available for pollination.

Arboretum
An outdoor “living museum” of woody plants (herbaceous plants such as garden perennials are usually not featured). Cf. Botanic garden.

Botanic garden
An outdoor “living museum,” usually featuring both woody and herbaceous plants. Cf. Arboretum.

Botany
The science and study of plants and of other non-animal organisms. Cf. Horticulture.

Canker
An open, sunken, or patch-like zone of diseased tissue on a plant stem.

Conifer
A gymnosperm (see below) that bears cones. Examples; pine, fir, spruce, Douglas fir, larch, bald cypress, dawn redwood.

Crown
The sum of the leaf-bearing branches of a tree. The term is also used by some arborists for the junction of the trunk and the root system.

Cultivar
A contraction of “cultivated variety”—in other words, an artificially selected variety. Rendered in Latin as “cultivarietas,” which is almost certainly a neologism.

Endemic
Referring to a plant species that is native to only one geographic area.

Exfoliate
To peel away, often in patches or strips.

Fascicle
The bundle-like structure that pine needles are contained in. 

Fruit
The developed/fertilized ovary of a flower. Only flowering plants bear fruit. Hence, the cones of such nonflowering plants as conifers (pines, firs, yews, etc.) are not synonymous with fruit. The ginkgo is also a primitive, nonflowering plant. It produces a seed with a fleshy covering (aril). This is not a fruit, either.

Gymnosperm
A “naked seed” plant. Gymnosperms do not produce true flowers or fruit. Instead, they reproduce by means of cones (conifers) or seeds sheathed in a fleshy structure called an aril (ginkgos and yews). Cf. Angiosperm.

Habit
The overall shape of a tree, as seen from some distance.

Herbaceous plant
A plant that does not develop woody tissue. These plants are usually not featured in arboreta.

Horticulture
The art and science of growing and using ornamental plants.

Living Fossil
A currently extant species that has a demonstrably long fossil record. Examples: ginkgo, dawn redwood.

Opposite
Referring to a phyllotaxy (see below) in which there is a pair of leaves at each stem node.

Phyllotaxy
The arrangement of leaves on a stem. See also Opposite, Alternate, and Whorled.

Shade Tree
In our purposefully restrictive definition, any tree of spreading habit and relatively dense crown that has its lowest branches high enough for a person to walk under it without bowing his or her head. Hence, a European beech, which usually has branches almost down to the ground, is not a shade tree.

Shrub
A woody plant with many first-order stems. Usually 15 feet or shorter at maturity.

Taxon
Any valid level of biological classification, from kingdom all the way down to such subspecific levels as variety and cultivar.

Tree
A woody plant with one, or at most a few, first-order stems (trunks). Usually more than 15 feet tall at maturity.

Whorled
Referring to a phyllotaxy (see above) in which there are three or more leaves at each stem node.