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ELEMENTARY STUDIES IN BOTANY 



The most notable protective structure in plants of dry 

 regions, aside from the ever-present epidermis and cuticle, 

 is the water storage tissue. This is not a protection against 

 loss of water, but the same end is accomplished by storing 

 water. Usually the water reservoir is a definite tissue, 

 often being distinguished from the green working cells in 

 leaves by being a group of colorless cells (Fig. 173.) In 



FIG. 174. Agave (maguey), showing rosette of fleshy leaves. Photograph by LAND 

 near San Luis Potosi, Mexico. 



regions of perpetual drought, the leaves may become thick 

 and fleshy on account of extensive water storage tissue, as 

 in the agave (Fig. 174). In the cactus the leaves have been 

 abandoned as foliage organs, and the peculiar stems have 

 become great reservoirs of water. The globular body, so 

 common a cactus form (Fig. 175), may be taken to represent 

 the form of body by which the least amount of surface may be 

 exposed and the greatest amount of water storage secured. 

 In the case of these fleshy leaves and bodies, it has long been 



