some of the most interesting and highly developed succulents in all the world. Because they inhabit the driest parts of South Africa, where at times rain does not fall once in two years, these plants have perfected the devices of succulence to the highest possible degree.

They have reduced themselves to one or two pairs of thick, ileshy leaves to serve as perfcct waier reservoirs. Thc\ have become nearly round in shape to contain the greatest volume of moisture with the least possible surface exposed to evaporation. They have learned to lie low in the long months of drought with their new growths wrapped in a papery envelope of old leaves, or buried in the soil with only the leaf tips exposed. And to compensate for burying themselves in tins way—which puts their breathing pores and chlorophyll cells underground, where air and sunlight cannot reach them—they have learned to transpire through their sides and to admit sunlight to their green cells within through translucent windows developed in their leaf tips exposed aboveground. But despite these wonders the most remarkable feats of these plants lie in the realm of protective imitation, camouflage, and mimicry.

We are all familiar with protective form and coloring among animals and insects, and we have even seen instances of mimicry among the Living Rock Cacti. But the most numerous and perfect mimics in all the plant world are the stone mimics of the Mesembrvanthemum family. In order to survive in their rainless habitat these plants, have not only had to economize, store, and lie low, but protect themselves from the thirsty desert animals who would devour them instantly for their juicy flesh. Without the defense of spines or teeth, a tough skin or unpleasant taste, they have chosen instead to simulate the rocks and pebbles among which Ihey grow. And so nearly do they re.semble these stone* in color, texture, and shape thai they are practically invisible in their native habitat except when in bloom. Fortunatclv this brief

0 0

Post a comment