Deserts
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Hot and Dry Deserts vegetation is very rare. Plants are almost all ground-hugging shrubs and short woody trees. All of the leaves are replete (packed with nutrients). Some examples of these kinds of plant are Turpentine Bush, Prickly Pears, and Brittle Bush. For all of these plants to survive they have to have adaptations. Some of the adaptations in this case are the ability to store water for long periods of time and the ability to stand the hot weather.
Cold Deserts plants are scattered. In areas with little shade ,about 10 percent of the ground is covered with plants. In some areas of sagebrush it reaches 85 percent. The height of scrub varies from 15 cm to 122 cm. All plants are either deciduous and more or less contain spiny leaves.
One of the important life group in the desert is formed by atrophied trees and bushes. they are normally found in sandy deserts, although they are in almost all desert areas.
Trees and shrubs in the desert get water from deep underground, thanks to their very long roots, which can reach up to 246 feet (75 meters). Also, these roots keep the plants held fast to the surface, especially if they manage to get hold of a solid rock.
During the dry season, many of these shrubs and trees have very few leaves if any at all. when the driest season arrives, they lose their leaves and some of their branches and breathe through the porous bark of their trunks. Woody tissue of the trunks and main branches are very strong and main branches are very strong and resistant to the effects of the sun, and some bushes can dry out all the way without dying.
Cacti develop thorns in stead of leaves. These thorns are very useful: first, they are hard and very sharp, to dissuade animals that might try to devour a cactus; secondly, they provide shade for the stem and collect the dew; and third, the thorns traps trap a layer of air around the plant to reduce the amount of evaporated moisture, forming a barrier against the hot, dehydrating air.
Chlorophyll appears on the stems and on the exterior tissue of the plant,since there are no leaves. That way, photosynthesis can be carried out without wasting any water.
The Creosote bush is one of the most successful of all desert species because of its combination of many adaptations. It has tiny leaves which close their stomata during the day to avoid water loss and open them at night to absorb moisture. It has an extensive double root system