Observations of putative pollinators of Hemipilia flabellata Bur. et Franch. (Orchidaceae) in north-west Yunnan Province, China

Interactions between Hemipilia flabellata and anthophilous insects were stu died in northwestern Yunnan, China during June-July of 1996 and 1997. Twent y-seven species of insects were seen visiting the flowers of this species, although only male and female individuals of the bee Anthophora mangkamensi s Wu were observed carrying the pollinaria. The frequency of visits by A. m angkamensis to this orchid was rather low. Pollinating bees normally sample d only th; lowermost flowers in an inflorescence, staying for 1-3 seconds. This species is also characterized by low pollination, low fruit set (1-22% ) and a very striking decrease in fruit production from bottom to top of th e inflorescence. All of these indicate that the orchid may rely on deceptio n to attract visitors. Ajuga forrestii Diels (Labiatae) appears to be the m ain or exclusive subsidiary nectar source for A. mangkamensis during the fl owering period of H. flabellata. It appears that H. flabellata utilizes a f ood deceit pollination strategy for pollination. The orchid benefits from t he great variation of flowers in colour and shape. Phenological, functional -morphometric and distribution data indicate that A. mangkamensis is an opt imal pollinator of H. flabellata and thus the anthecological adaptation of the orchid to the pollen vector may be unique. (C) 1999 The Linnean Society of London.