Molecular Biology and Genetics
Statistics of barcoding coverage
Specimen Records: 13
Specimens with Sequences: 16
Specimens with Barcodes: 16
Species With Barcodes: 5
Public Records: 6
Public Species: 3
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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 in which the leaves are borne in spirals and are deciduous.
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 (typically less than 1 milligramme when ripe) globular, brown seeds.
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, Rossularia, 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, as well as those that formerly were included in the genus Cotyledon, are poisonous, even dangerously poisonous. 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 (allegedly successfully). One thing that is clear is that the species vary in their activity, ranging from allegedly edible to deadly, so it is best to regard all species as dangerous until otherwise demonstrated.
As succulents go, Cotyledon spp. certainly are rewarding garden and indoor subjects, practically independent of irrigation in all but full desert conditions, though they cannot survive poor light or bad drainage in the wet. Their main enemies are sucking bugs, members of the suborder Auchenorrhyncha such as the mealy bug (Pseudococcus) and similar insects. Though not spectacular, they are elegantly decorative and often interesting in shape. The inflorescences of the larger species often make fine components of dried arrangements in floral design.
Species include (among others):
- Cotyledon adscendens
- Cotyledon barbeyi
- Cotyledon campanulata
- Cotyledon cuneata
- Cotyledon chrysantha
- Cotyledon elisae
- Cotyledon galpinii
- Cotyledon orbiculata – Pig's Ear, Round-Leafed Navel-Wort
- Cotyledon papilaris
- Cotyledon tomentosa - Bear's Paw
- Cotyledon undulata - Silver Crown, Silver Ruffles
- Cotyledon velutina
- Cotyledon woodii
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- Dyer, R. Allen, “The Genera of Southern African Flowering Plants”. ISBN 0-621-02854-1, 1975
- Plants of southern Africa: Names and distribution (Memoirs van die Botaniese Opname van Suid-Afrika). Pretoria: National Botanical Institute. 1993. ISBN 1-874907-03-X.
- Paterson-Jones, Colin; Manning, John (2008). Field Guide to Fynbos. Cape Town: Struik Publishers. ISBN 1-77007-265-9.
- Watt, John Mitchell, Breyer-Brandwijk, Maria Gerdina: The Medicinal and Poisonous Plants of Southern and Eastern Africa 2nd ed Pub. E & S Livingstone 1962
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