Observations on the pollination of Pelargonium tricolor, section Campylia (Geraniaceae)

A group of four species of Pelargonium L’Hérit. in the section Campylia (Sweet) DC. have embossed ‘warty areas’ at the bases of the posterior petals of the zygomorphic flowers. In Pelargonium tricolor Curt, these embossed areas are most distinctive. The significance of these embossed areas in the attraction of insect pollinators is discussed. From repeated observations of P. tricolor it is concluded that these areas are false nectaries and that they are effective in attracting dipteran pollinators. Megapalpus capensis Wiedemann (Diptera: Bombyliidae), in particular, exhibits strong association with these false nectaries. It is further predicted that the embossed areas on the petals of the remaining three species in the group, namely P. capillare (Cav.) Willd., P. ocellatum J.J.A. van der Walt and P. incarnatum (L’Hérit.) Moench have similar value for attracting anthophilous insects