Cactaceae

Cactaceae

•  Succulence helps the barrel cactus resist drought. In dry weather the plant becomes shriveled as stored water becomes low. In wet weather the barrel cactus grows plump as special storage cells fill up with water.
• The cacti may contain 80% water in their bodies. 
• The larger cacti need stronger structures to support their weight, and consequently they may be ribbed with woody tissues, much like an internal skeleton. 
• in spite of it lack of leaves, the cacti carry on the same work of photosynthesis that other green plants do. It simply transfers the process from the leaves to the stems. A cactus is green all over, which means that the chlorophyll is present in all the external above-ground parts.
• The spines of the cacti can also cast shadows; not very big shadows, but a cactus that is covered with tens of thousands of spines may get a good deal of safe. The spines break up the sun's rays and help keep the plant from getting the air currents that pass over the surface of the plant, thus reducing loss of moisture from evaporation. At the same time this results in a reduction of the plant's ability to lose heat to the surrounding air.
• Cacti vary greatly in form. Some are tiny plants only an inch or so high, while others tower thirty-five feet or more above the desert floor. Each species has its own arrangement of spines, in twos or threes, in starlike clusters, or in long straight rows. Some have pads, others are plump and round, and a few are treelike.
• Of the nearly 1000 kinds of cacti known, more than half grow in Mexico and the southwestern United States.

• Cacti represent an iconic component of California's desert landscapes. The cactus family is a sepcies-rich group containing about 125 genera and 1,800 species. Although the cactus flora of California is large, it is less diverse than the Sonoran Desert area of Arizona and far less rich than the Chihuahuan Desert of Mexico. "California Desert Plants, Philip W Rundel, Robert J Gustafson, Michel E Kauffmann."