Charles Day is Wave Hill’s Ruth Rea Howell Senior Horticultural Interpreter.
This week, our little concertina plant (Crassula rupestris) is putting on its annual display of neatly clustered pink flowers in the Cactus and Succulent House, the right-hand wing of the Marco Polo Stufano Conservatory.
Found in the wild in some of the drier parts of South Africa and Namibia, it grows naturally in rocky places—rupestris indicates this affinity for rocks—and has several tricks to enable it to survive and spread in its arid environment. A slow-growing habit means that it requires less water than a more vigorous plant, and its thick, succulent leaves are able to retain moisture during prolonged droughts.
Flowering is followed by the release of masses of tiny, dust-like seeds. In the wild, the lightest gust of wind would scatter them across the parched landscape. A small number might happen to lodge themselves in a crevice where water lingers following night dews or the occasional rain shower. If they are lucky, this might be enough to allow for germination and growth.
The genus Crassula contains hundreds of species from many parts of the world. All are succulents, but it is mainly the species from Southern Africa which are the most interesting for ornamental use. The name comes from the Latin Crassus, meaning solid or thick, alluding to their fleshy foliage.