| Crassula
This genus (a member, naturally, of the Crassulaceae or stonecrop family) of well over a hundred species includes some of the most familiar and easily grown succulent plants, and also some rare, extremely interesting, and quite demanding plants. The crassula that everyone in coastal California knows is the jade plant, Crassula ovata (also called C. argentea or C. portulacea). Oddly enough, only a relatively few species in the genus share the jade plant’s appearance of a dwarf, freely branching tree with thick, round succulent leaves. In their native South Africa these few species are fairly widely distributed, growing in both summer and winter rainfall areas, and in cultivation they demand little more than bright sunlight, reasonably well drained soil, a decent amount of water and shelter from occasional hard frosts.
A number of other crassulas share the same general leaf shape as the jade plant, but their stems are much less massive, resulting in species that more-or-less sprawl over the ground, though slowly and without ever covering much space. These crassulas grow about as easily as jade plants and are well suited for small scale outdoor rock gardens, mixed plantings in container, or windowsill plants.
A more interesting group of crassulas includes those small and medium-sized species with oppositely paired wedge or triangular shaped leaves closely attached to the stems. The stems of some of these plants are tall growing with the leaves spaced out along them, while others have very abbreviated stems with leaves tightly packed.
In habit these plants approach the truly exotic members of the genus. In these the leaves are not only densely set on the stems, they are thickened and very succulent, and often light blue or blue-gray in color. Plants with this appearance are not generally suited for outdoor growing even though in nature they grow in winter rainfall areas. They require the brightest possible light, rapidly draining soil mixes and a dry summer resting period. Compounding the contrary nature of their cultivation, they need the brightest light exactly when the days are short and often gloomy. Under ideal circumstances they should be watered about once a week when they’re actively growing, but this schedule should be modified if the days are too dark to allow more time between waterings. Keeping these plants healthy is a bit of a challenge, but their uniquely architectural shapes justify the extra care they need.
Sharing these densely columnar plants’ habits are other exotic crassulas including plants with windowed leaf surfaces or leaves covered with dense hair. Other odd crassulas include miniature caudiciforms, small, shade loving plants with large red and purple leaves, and even a few annual or aquatic species. Some of these odder plants are very rare both in the wild and in cultivation.
The Garden has a good collection of Crassula with a number of species available for purchase. Anyone who gives the genus a little time and close observation will find it an exception to the old saying about familiarity breeding contempt.
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