Cotyledon (genus)


Cotyledon is a genus of succulent plants in the family Crassulaceae. Mostly from Southern Africa, they also occur throughout the drier parts of Africa as far north as the Arabian peninsula.

Description

Members of the genus are shrublets, generally succulent, with fleshily woody, brittle stems and persistent succulent leaves.
The leaves are opposite. Leaf pairs generally are oriented at 90 degrees to their preceding and following pairs, as is common in the family Crassulaceae, but the leaf habit differs from say Tylecodon.
The flowers are pendulous and tubular, borne at the tips of stout, rather long peduncles, mainly in short cymes. Calyx 5-partite, corolla 5-lobed. Petals united in a tube or urn that generally is longer than broad, their triangular tips more or less pointed and recurved, 10 stamens arising from corolla near base and projecting or nearly projecting from the corolla. Gynoecium comprises 5 carpels, nearly or quite free, each carpel tapering into a slender style with an obliquely capitate stigma. Each carpel contains many small globular, brown seeds.

Taxonomy

Until the 1960s there were about 150 species described as being in the genus Cotyledon. However, since then it has been split into at least Adromischus, Dudleya, Rosularia, and Tylecodon, leaving probably less than two dozen species in Cotyledon. Of these, about four are characteristically fynbos plants.

Cultivation and uses

Most plants in the genus, and those that used to be included in the genus Cotyledon, are poisonous, even dangerously so. Some have been implicated in stock losses among goats, pigs and poultry. However, many species have long been used in traditional medicine. They have been applied for many purposes, ranging from magic charms to removal of corns.
Cotyledon spp. are grown as garden and indoor subjects, practically independent of irrigation in all but full desert conditions, though they cannot survive poor light or bad drainage. Pests that affect them include sucking bugs, members of the suborder Auchenorrhyncha such as the mealy bug, and similar insects. The inflorescences of the larger species are sometimes used as components of dried arrangements in floral design.

Species list

Species include :