New taxa from the arid regions of southern Africa

Four new taxa from the semi-desert parts of southern Africa are described: Xysmalobium fluviale (Asclepiadaceae) from Prince Albert in the southern Cape; X. gomphocarpoides var. parvilobum which is widespread from Beaufort West to Caledon; Euphorbia suffulta (Euphorbiaceae) from the region between Merweville and Rietbron also in the southern Cape and Tylecodon cremnophilus (Crassulaceae) from the Rosyntjie Mountain in the Richtersveld. All taxa are illustrated with line drawings