A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike , shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from by their multiple Plant stem and shorter height, less than tall.
Some definitions state that a shrub is less than and tree is over 6 m. Others use as the cut-off point for classification. Many species of tree may not reach this mature height because of hostile 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. In terms of longevity, most shrubs fit in a class between Perennial plant and trees; some may only last about five years even in good conditions, others, usually the larger and more woody ones, may live to 70 or more, but on average they last 7-10 years.
Shrubland is the natural landscape dominated by various shrubs; there are many distinct types around the world, including fynbos, maquis shrubland, shrub-steppe, shrub swamp and moorland. In gardens and parks, an area largely dedicated to shrubs (now somewhat less fashionable than a century ago) is called a shrubbery, shrub border or shrub garden. There are many garden of shrubs, bred for flowering, for example , and sometimes even leaf colour or shape.
Compared to trees and herbaceous plants, perhaps a relatively small number of shrubs have agricultural or commercial uses. Apart from the several berry-bearing species (using the culinary rather than botanical definition), few are eaten directly, and they are generally too small for much timber use unlike trees.Rosewood does not come from roses. Those that are used include several perfumed species such as lavender and rose, and a wide range of plants with medicinal uses. Tea and Coffea are on the tree-shrub boundary; they are normally harvested from shrub-sized plants, but these would be large enough to become small trees if left to grow instead.
Small, low shrubs, generally less than tall, such as lavender, Vinca and most small garden varieties of rose, are often termed as .
Most definitions characterize shrubs as possessing multiple stems with no main trunk below. 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 without a reasonable length beforehand. Many trees can grow in multiple stemmed forms also while being tall enough to be trees, such as oak or ash.
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.
For shrubs that are high the following structural forms are categorized:
For shrubs less than high the following structural forms are categorized: