Named after Henri August Duval (1777-1814), a French botanist and physician, the genus Duvalia comprises small stem succulent plants with a creeping or mat forming habit, growing generally in the shade of shrubs. The distribution is disjunct, with section Arabica species found in the Arabian peninsula and the Horn of Africa, i.e. Saudi Arabia, Yemen, Sudan, Djibouti, Ethiopia and Somalia in the north, whilst section Duvalia comprises species from southern Africa which are found in Botswana, Malawi, Mozambique, Namibia, Zambia, Zimbabwe, and South Africa.
Whilst hybrids are unknown in habitat, open pollination under greenhouse conditions has produce a number of interesting crosses.
Found only in the Great Karoo area of the Eastern and Western Cape Provinces grows in sandy pans in semi arid conditions. It is characterised by its spider like corolla and pure white corona. The plant shown was grown from seed in 2000 and flowered the following year.
From the Northern, Eastern and Western Cape Provinces of South Africa, Duvalia caespitosa has two varieties; var. caespitosa and var. compacta. The latter can be distinguished by its smaller annulus and has glabrous corolla margins as opposed to the vibratile hairs on the margins of var caespitosa. In the Calitzdorp area of the Cape, Duvalia caespitosa is found to produce a natural hybrid with Huernia pillansii [PVB1213].
From the central South African regions of the Great and Upper Karoo, this species is easily identifiable by its thick six angled stems and its relatively large fleshy and very hairy flowers, reminiscent of the section Arabica species Duvalia sulcata.
Another species with hairy flowers is Duvalia elegans, although both stems and flowers are considerably smaller than in Duvalia corderoyi. This species from the Little Karoo and the Worcester-Robertson Karoo in the Western Cape Province has also been reportedly found [but never re-discovered] in Namibia. It seems to favour more humid conditions in cultivation.
A rare species from the Eastern Cape, clsely related to D. angustiloba, D. maculata and D. modesta
Also favouring humid conditions, this species from the coastal areas of the Western Province has cylindrical rhizomatous green stems and easily recognisable flowers.
With the disjunct distribution of Namibia, the Northern Cape and Eastern Cape Provinces this aptly named species is instantly recognisable. The seeds of this species are also unique in having distinctively undulating wings.
This species can be found in a large range of habitats in a relatively large area of the Eastern Cape Province of South Africa. It is very similar to Duvalia caespitosa from which it can be distinguished by its more delicate stems and smaller annulus. The plant shown is one of the oldest in my collection having been obtained in 1994 and still going strong.