On the fertilization of Grammatophyllum
This short note by H. N. Ridley discusses the role of insects in the fertilization of Grammatophyllum and related orchids, with a broader observation on insect-mediated pollination failure.
Summary
Ridley argues that if the lip of Grammatophyllum were immobile, the orchid would be able to exploit all three insect pollinators and avoid the loss of flowers through honey removal without fertilization. He identifies carpenter bees as harmful to this orchid, noting their parallel behaviour of tearing open the base of the corolla tube of Ipomoea palmata to access honey, thereby preventing fertilization (p. 229).
Ridley extends the observation to a broader point: a considerable number of flowers, especially of introduced plants, never set seed due to insect actions that fail to effect pollination. He cites Clerodendron macrosiphon, a Zanzibar shrub with long tubular white flowers evidently adapted for hawkmoth pollination, which opens its flowers too early for the intended pollinators. Small Trigona bees then collect all the pollen from the stamens without touching the stigma, and the plant has never produced a single fruit in his experience (p. 229).