A shrub or bush is a small- to medium-sized perennial woody plant. Unlike , shrubs have persistent woody stems above the ground. Shrubs can be deciduous or evergreen. They are distinguished from by their multiple Plant stem and shorter height, less than 6 m-10 m (20 ft–33 ft) tall.
Definition
Shrubs are perennial woody plants, and therefore have persistent woody
Plant stem above ground (compare with
).
Usually shrubs are distinguished from trees by their height and multiple stems. Some shrubs are
deciduous (e.g.
Rhaphiolepis) and others
evergreen (e.g.
holly).
philosopher
Theophrastus divided the plant world into trees, shrubs and herbs.
Height
Some definitions state that a shrub is less than 6 m and tree is over 6 m. Others use 10 m as the cut off point.
Many species of tree may not reach this mature height because of less than ideal growing conditions, and resemble a shrub sized plant. However such species have the potential to grow taller under the ideal growing conditions for that plant.
Small, low shrubs, generally less than 2 m (6.6 ft) tall, such as lavender, Vinca and most small garden varieties of rose, are often termed .
Multiple stems
Most definitions characterize shrubs as possessing multiple stems with no main trunk.
This is because the stems have branched below ground level. There are exceptions to this, with some shrubs having main trunks, but these tend to be very short and divide into multiple stems close to ground level. Many trees can grow in multiple stemmed forms also, such as
oak or ash.
Use in parks
An area of cultivated shrubs in a
park or a
garden is known as a
shrubbery.
When clipped as
topiary, suitable species or varieties of shrubs develop dense
foliage and many small leafy
growing close together.
Many shrubs respond well to renewal
pruning, in which hard cutting back to a "
Living stump" results in long new
Plant stem known as "canes". Other shrubs respond better to selective pruning to reveal their structure and character.
Shrubs in common garden practice are generally considered flowering plant, though some smaller Pinophyta such as mountain pine and common juniper are also shrubby in structure. Species that grow into a shrubby habit may be either deciduous or evergreen.
Botanical structure
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 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.
[Costermans, L. F. (1993) Native trees and shrubs of South-Eastern Australia. rev. ed. ]
For shrubs high the following structural forms are categorized:
-
dense foliage cover (70–100%) — closed-shrub
-
mid-dense foliage cover (30–70%) — open-shrub
-
sparse foliage cover (10–30%) — tall shrubland
-
very sparse foliage cover (<10%) — tall open shrubland
For shrubs less than high the following structural forms are categorized:
-
dense foliage cover (70–100%) — closed-heath or closed low shrubland—( North America)
-
mid-dense foliage cover (30–70%) — open-heath or mid-dense low shrubland—( North America)
-
sparse foliage cover (10–30%) — low shrubland
-
very sparse foliage cover (<10%) — low open shrubland
List of shrubs
Those marked with * can also develop into tree form.
- A
- B
- C
- D
- E
- F
- G
- H
- I
- J
- K
- L
- M
- N
- O
- P
- Q
- R
- S
- T
- U
-
Ulex (Gorse)
-
Ulmus pumila celer (Turkestan elm – Wonder Hedge)
-
Ungnadia (Mexican Buckeye)
- V
- W
- X
- Y
- Z
