Prostrate Shrub

a shrub having horizontal or suberect axial shoots that grow for a long time in length but for a limited time in thickness. As a result of this pattern of growth, the stems and branches are very elastic. Prostrate shrubs often live 1,000 years or longer. Together with prostrate trees and undershrubs, they constitute a special morphogenetic series of life-forms of woody plants. They appeared as adaptations to conditions unfavorable for the growth of erect trees and shrubs.

Prostrate forms are the principal components of the plant cover in subarctic and subantarctic regions, in the mountains of temperate and tropical zones, and along ocean shores; particularly common are Krummholz (elfinwoods) of Swiss mountain pine, dwarf stone pine, dwarf birch, willow, and heath. Prostrate shrubs help control soil erosion. There are more than 1,000 species of woody plants having a genetically determined prostrate form; 200 species occur in the USSR. Many species of forest trees, including larch and beech, occur as prostrate forms on mountain summits and in the northernmost parts of forests.