Thursday, February 4, 2016
Posted by Becky Brinkman
Paphiopedilum gratrixianum, a tropical Asian slipper flowering now in the Orchid Center, is an example. Tropical slipper orchids are thought to be pollinated by flies, though most of the evidence is indirect. There simply aren't a tremendous number of field studies documenting slipper orchid pollination. So, although I don't know exactly which insect pollinates Paphiopedilum gratrixianum, it's possible to make a fair guess, based on a study of a closely related species, Paphiopedilum villosum. A field study (Bänziger 1996) of P. villosum reported pollen capture by hover-flies and the author suggested that the hover-flies are lured by food deception.
Pollination using a food lure (real or fake) is a fairly common mechanism across the plant kingdom and involving different types of pollinators. But in orchids, the anatomy for deception and manipulation of winged insects has evolved to an extraordinary degree. Yes, the pouch is a trap, but in the same way that the bucket of a Coryanthes flower is a trap. It's a trap that facilitates pollination.