The Tender Trap

Few creations of nature are more exotic than the flowers that trap insects in order to transfer pollen from their male to their female reproductive organs. Though the workings of these trap flowers were known by Charles Darwin, their intricate mechanisms are only now coming to light.

Modern plant research, writes German Biologist Stefan Vogel in Um-schau, has supplied a sudden flood of knowledge about the behavior of trap flowers. Their blossoms range from one-half inch to two feet in length. They lure insects to their traps by the unfloral smell that their osmophores give off during the "lure phase"; yet even the smells vary--from fecal-like, to cidery, to urine-like, to musky.

So Sticky & Warm. The trap of just about all such flowers is a hollow tunnel formed by the flower's blossom that botanists call the caldron. Some varieties of trap flowers are equipped along their rims with countless tiny hairs, which appear to an approaching insect to be other fluttering insects. Once it lands on the camouflaged rim, the decoyed bug is helpless, the victim of a slippery substance that can neutralize the suction cups on a fly's feet. No matter how it struggles, the bug slides into the caldron's pit.

The numerous species of traps use ingenious methods to cover the insects imprisoned in the blossom with the sticky pollen that they carry to the flower's close-at-hand female sex organ as they try to escape. After a night inside the Aaron's-rod flower, mosquitoes find themselves literally snowed under by pollen, while flies caught by the lily-like arms of another trap flower must wade through mounds of pollen to move from one part of the caldron to another. The curved hollow of the purplish-green Dutchman's-pipe is pocked on the inside by windowlike patches that are surrounded with pollen, which rubs off on the bug who mistakes the bright patch for daylight and freedom. Often the caldron provides warmth and humidity: sometimes it also supplies a nectar to keep the prisoner pollinating for as long as 100 hours.

Free, for a While. Once pollination is over, the insect is usually permitted to fly free, if only to be victimized by another flower. One erect and fleshy trap flower lets its prisoner fall out by merely drooping its blossom downward. The male part of the jack-in-the-pulpit allows mosquitoes to escape by opening a small hatch. But the mosquito had better be alert; its otherwise identical female part has no such escape hatch.

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