Description: Catasetums are noteworthy for their unique dimorphic flowers. The male and female flowers are so morphologically different that John Lindley originally treated them as seperate genera!. They also display one of the most advanced pollination mechanisms which is outlined below.
Bees of the genera Eulaema, Euplusia and Euloglossa are mainly responsible for pollination of Catasetum. In most Catasetum species the male flowers begin to emit a strong musky odour 2-3 days after opening. Male bees are attracted by this, enter the flower and proceed to scratch at the source of the odor which is normally directly beneath the antennae at the base of the column. The bees touch an antenna and this moves the rostellum which holds the viscidium in place. The viscidium is released and is thrown by the tension bound stipe onto the back of the bee. The sticky secretion of the viscidium set rapidly and the stipe hangs down along the dorsal midline of the bee's abdomen. By the time the bee enters a female flower, the anther-cap has fallen off revealing the large pollinia which then hang in the correct position to be placed on the stigmatic surface of the non-resupinate female flower.

The Manual of Cultivated Orchid Species, Bechtel, Cribb & Launert Hortus Third, LH Bailey Hortorium, 1976

Orchidaceae

Subfamily Cypripedioideae Tribe Cypripedieae