Shrub
- For the place in California, see Shrub, California.
A shrub or bush is distinguished from a tree by its multiple stems and lower height, usually less than 5–6 m (15–20 ft) tall. A large number of plants can be either shrubs or trees, depending on the growing conditions they experience. Small, low shrubs such as lavender, periwinkle and thyme are often termed subshrubs.
An area of cultivated shrubs in a park or garden is known as a shrubbery. When clipped as topiary, shrubs generally have dense foliage and many small leafy branches growing close together. Many shrubs respond well to renewal pruning, in which hard cutting back to a 'stool' results in long new stems known as "canes". Other shrubs respond better to selective pruning to reveal their structure and character.
Shrubs in common garden practice are generally broad-leaved plants, though some smaller conifers such as Mountain Pine and Common Juniper are also shrubby in structure. Shrubs can be either deciduous or evergreen.
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[edit] Shrubs as a botanical structural form
In botany and ecology a shrub is more specifically used to describe the particular physical structural or plant life-form of woody plants which are less than 8 m high and usually have many stems arising at or near the base.
For example, a descriptive system widely adopted in Australia is based on structural characteristics based on life-form, plus the height and amount of foliage cover of the tallest layer or dominant species.[1]
For shrubs 2–8 m high the following structural forms are categorized:
- dense foliage cover (70–100%) — closed-scrub
- mid-dense foliage cover (30–70%) — open-scrub
- sparse foliage cover (10–30%) — tall shrubland
- very sparse foliage cover (<10%) — tall open shrubland
For shrubs less than 2 m high the following structural forms are categorized:
- dense foliage cover (70–100%) — closed-heath
- mid-dense foliage cover (30–70%) — open-heath
- sparse foliage cover (10–30%) — low shrubland
- very sparse foliage cover (<10%) — low open shrubland
[edit] List of shrubs (bushes)
Those marked * can also develop into tree form.
[edit] References
- ^ Costermans, L. F. (1993) Native trees and shrubs of South-Eastern Australia. rev. ed. ISBN 0947116761
