Saturday, May 28, 2005

If the shoe fits

Lady's slipper. Moccasin flower. Squirrel shoes. The scientific name is Cypripedium, which is Greek for "slipper of Venus." Doesn't look much like a shoe to me, but the pink lady's slipper is certainly the most spectacular wildflower of New England, and this is its season.

The blossom fairly forces cross-pollination: that is, pollination by a plant other than itself, which may yield hardier stock. There are two ways for an insect to enter the flower: through the long, inward-curving slit at the front of the big, pink sac, or through two little holes at the top of the sac that are hidden by petals. Attracted by color or scent, the insect invariably enters at the front, and soon discovers it has passed through a one-way door into a voluminous chamber, lush with nectar but with no obvious exit.

If the insect persists in its explorations, it will find its way toward the two escape holes at the top of the sac. Forcing its way upward through a narrow passage toward freedom, the insect must first encounter the female part of the plant, the stigma, which is equipped with tiny bristles, like a lint-brush. The brush removes from the body of the insect whatever pollen it has carried from another lady's slipper.

But escape is not yet complete. The insect struggles on toward one of the small round exits, where a male part of the plant, an anther, almost blocks its way. Forcing passage, the insect becomes covered with pollen. Free at last, it is ready to pollinate whatever plant it visits next, although one wonders why, after so much trouble, it has not learned to leave well enough alone.