COLORED POLLEN IN CACTACEAE - A MIMETIC ADAPTATION TO HUMMINGBIRD-POLLINATION

Pollen of 361 species from 71 genera of Cactaceae was investigated for this study of the correlation between pollen colour and the pollinati on syndrome. 11% of all species studied had red or brown pollen, and n early all of these species were ornithophilous. This suggests that pol len colour probably is part of the bird-flower syndrome of Cactaceae. Possibly the red or brown pollen might be a crypto-mimetic adaptation to the dark coloured bill of the pollinating hummingbird (Trochilidae) and secures safe transport to a receptive stigma without being remove d by the bird immediately. The results are discussed against a backgro und of studies encompassing about 900 species from 77 families, which provide further evidence for the proposed adaptive significance of pal ynological characters.