Throwing Spears and Snapping Lips

Plants wave in the breeze, bend toward light, and gradually furl and unfurl their parts, though Usain Bolt doesn't spend his time worrying about competition from plants. But at least two groups of orchids have evolved fairly speedy movements, at least by plant standards (admittedly not that high). Both occur in flowers and both involve manipulating pollinators.

Male Catasetum genus flowers fire their sticky pollinia when a trigger hair is disturbed. The motion is so fast it is hard to see in real time (move over Usain!). Under natural conditions the flower hopes they stick to the male euglossine bee that was investigating the flower, and that the bee will later visit a female flower and complete their rather tenuous copulation. If you use a well-positioned toothpick to activate the trigger, the pollinia will shoot halfway across the room. Catasetum, by the way, is one of the few orchid groups that have separate male and female flowers, usually found on separate plants. Most orchids are bisexual (also called perfect), with both pollen and ovary carried on the same flower, though they usually don't self-fertilize. Like birds of paradise, it is the male flowers that are showy - the female flowers are typically smaller and green and look a bit like a Little Green Riding Hood. 

Porroglossum genus flowers are slower, but their plan is similar - attach sticky pollinia to a pollinating fly. The entire lip of a Porroglossum flower is hinged and when sufficiently disturbed it snaps up against the column, trapping the fly in place for pollen transfer either onto or off of the fly. Okay, "snaps" is a bit strong - we are not talking great white shark or chameleon tongue here. How about "closes up against the column". It typically takes several seconds, but apparently it is enough to trap a fly (move over Mr. Miyagi!). I am speculating now, but maybe if it moved faster it would scare the fly into flight. In any case, the lip opens again after several minutes, releasing the insect. The hapless fly presumably suffers briefly with post-traumatic stress syndrome, but eventually recovers enough to deliver its precious pay load to another snapping flower. And right back into psychotherapy for our doubly duped Dipteran.

You can find videos of both of these actions if you poke around on the web. I have a Porroglossum plant and will make a video when it flowers and post it on this blog!