blooming period occurs onlv during the rainy season, when all other vegetation is abundant and there is sufficient food

Tor browsing animals everywhere. When the ruins cease and the countryside dries again, the sione mimics quietly blend into the land once more,

Remarkable as this camouflage is, liowever, it must be understood thai these plants have not consciously imitated their surroundings It is actually a case of "survival of the finest.'w For over millions of years those sione-mimicry plants which could not easily be seen by predators have remained, propagated themselves, and been improved by natural selection until they have achieved this almost perfect means of protection.

Of the twenty or more genera containing sione-mimicr\ plants, windowed plants, or both, the genus Pteiospilos (ply-oh-spy'-los) is easily the most popular The pleiospiles arc all stone-mimicrv plants consisting of one or more pairs of very thick, distinctly separate, brownish gray-green leaves. These leaves are often angular in shape and covered with darker raised spots which give them a rough appearance, like the bits of weathered granite among which they grow. Although they may reach the size of a duck egg and often grow in large clusters, these leaves are virtually invisible as they lie half buried among the rocks until the showy two- or three-inch flowers appear- Pleiospilos bolusii is perhaps the best-known species in amateur collections, where its very heavy, angular, rocklike leaves make a plant four inches in diameter displacing golden yellow flowers in fall Two other species that are very similar and equally fine are the African Living Rock. P. simuian$f with longer, wider-opening leaves; and P.netik the Split Rock, with more compact, smoothly rounded leaves and bright, bronze-orange flowers in spring.

To many the most fascinating of alt mimicry and windowed plants are the seventy-odd species of the genus Lit hop* (lith'-ops). They are all very small, cylindrical or conical

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