NOTES ON RUSCHIA DICHROA (AIZOACEAE): AN ENDEMIC TO THE ARID MOUNTAIN FYNBOS OF THE WESTERN CAPE, SOUTH AFRICA

Ruschia dichroa (Rolfe) L. Bolus is endemic to a semi-arid, mountainous region within the Western Cape, South Africa. This species has often been confused with Ruschia marianae (L. Bolus) Schwantes and Astridia longifolia (L. Bolus) L. Bolus, since all three species have a similar chunky leaf morphology, are fairly large-flowered and may have reddish petaloid staminodes. Astridia longifolia only occurs in northern Namaqualand and is thus geographically well separated from the others, which are both found in the Wuppertal district of the Western Cape. The flowers of Ruschia dichroa differ from those of R. marianae by the presence of filamentous staminodes, which are collected into a cone around the stamens. In addition, the two species flower at different times, with R. marianae flowering from July to September and R. dichroa earlier in winter, from May to July. If not in flower, the two species can be separated by their different habit, R. marianae forming an erect shrub, whereas R. dichroa has a lower, more compact habit with decumbent, spreading branches. Ruschia dichroa differs from both A. longifolia and R. marianae by the finely serrated keels on its leaves, which are smooth in the other two species.