Deserts are found at latitudinal positions between 15^o to 35° North and South of the equator, and also in rainshadows.  They are the driest of all biomes.  The evaporation exceeds rainfall, making it very dry, with less than 30cm of rain per year.  Most deserts are very hot, but cold deserts also exist.  The hot deserts generally experience hot days and cold nights.  Hot deserts can be found in the southwest of the United States, along the coast of South America, in northern Africa, and in the Middle East.  There are cold deserts to the west of the Rocky Mountains, in eastern Argentina and throughout central Asia. 

The driest deserts receive too little rainfall to support any perennial vegetation.  In less arid regions, the plant life includes some grasses, shrubs, cacti, creosote, and rosette plants.  These plants have numerous adaptations to life in the desert, including:

• deep or spreading roots
• losing leaves (eg. prickly pear, ocotillo)
• thorns
• poisons
• annual habit - seeds
• CAM plants exchange CO2 at night

Periods of rainfall are marked by sudden and spectacular blooms of plants.

Terrestrial Biomes:

Desert
 Scrub