Aloe inconspicua: The first record of an exclusively insect-pollinated aloe

Most Aloe species are wholly or partly bird-pollinated, but a suite of seven Aloe species and two genera (Haworthia and Chortilirion) that likely belong within the Aloe clade (Asphodelaceae, subfamily Alooidea) share morphological characteristics suggestive of insect pollination. Field studies of one of these species, Aloe inconspicua, revealed that it is effectively and exclusively pollinated by insects, especially females of Amegilla fallax (Apidae) that visit its flowers for nectar and pollen. The small (7.9 mm ± SD = 2.0) white flowers produce a standing nectar crop of 0.097 ± 0.10 μl, much less than that of bird-pollinated aloes. Unlike other aloes studied to date, birds did not visit A. inconspicua, and bird exclusion had no effect on fruit or seed production. Visiting individuals of A. fallax typically contacted stigmas and anthers with their heads while accessing nectar, and single visits by them and a halictid bee resulted in seed set. Recent molecular evidence suggests that insect-pollination is the ancestral state for the Alooidea. If similar floral morphology indicates similar pollination systems, shifts from insect- to bird-pollination and possibly reversions back to insect pollination have occurred repeatedly within the ALOE clade.