NEW SPECIES OF ARISTEA SECTION RACEMOSAE (IRIDACEAE) FROM THE CAPE FLORA, SOUTH-AFRICA

Aristea fimbriata, A. inaequalis, and A. rupicola are new to this genu s of some 52 species of sub-Saharan Africa and Madagascar. The new spe cies all occur in the western part of the southern African winter-rain fall climatic zone and are highly local endemics, two of them known on ly from single extended populations. All three species have three-wing ed capsules, a specialized condition that defines subgenus Aristea, a taxon virtually restricted to the southern African winter-rainfall zon e. In addition the new species have pollen grains with apertures confi ned to one face of the grain, either monosulcate or trichotomosulcate, and have specialized, undivided styles that define section Racemosae, one of two sections of subgenus Aristea. Observations on the pollinat ion biology of A. inae qualis show that it is probably pollinated by f emale Anthophora diversipes (Anthophoridae) bees, which forage for pol len on the flowers of this species. This pollination strategy conforms to that of other blue-flowered species of the genus, that is, they ha ve flowers adapted for pollination by various species of female bees f oraging for pollen. A revised key to section Racemosae is presented, w hich includes entries for apparently undescribed taxa that require fur ther investigation.