[Chap. XIV THE RATE OF PHOTOSYNTHESIS 119 



and lima beans) are objects of common obsei-vation. Many tropical 

 orchids and bromeliads have aerial roots that become green when ex- 

 posed to light ( Fig. 55 ) . Roots of trees and many other plants are often 

 exposed to light through soil erosion. An examination of these exposed 



Fig. 55. The chlorenchyma of this Florida orchid is in the roots. It has no leaves 

 and very small stems. Photo by W. M. Buswell. 



roots is an easy way of discovering that chlorophyll may be formed in 

 the roots of many kinds of plants. There are many microscopic green 

 plants in which all parts of the plant body are green. Most of the body 

 of a moss or liverwort is ereen. The green stems of cacti are the most 

 conspicuous part of the plant; leaves are either temporary or entirely 

 absent. Wherever chlorophyll is present in plants, photosynthesis will go 

 on if other necessary conditions are suitable. 



