World's fastest plant explodes with pollen.

The fastest flower in the west, or anywhere else, is a woodland wildflower of North America called bunchberry dogwood, says a research team with a really fast camera.

A bunchberry dogwood (Cornus canadensis) bears flowers much like those of the beloved ornamental dogwood tree, but the entire bunchberry stands hardly knee high. Its tiny flowers span only a few millimeters and cluster at the center of four white, leaflike structures that casual observers mistake for petals.

Joan Edwards of Williams College in Williamstown, Mass., says that she started studying the flowers' pollen release after one of her students was examining some of them and exclaimed that something had "poofed."

A few botanists had noted the phenomenon before, but Edwards turned to high-speed photography to capture the flowers in the act of pooling. When a 1,000-frame-per-second video yielded a blurry view, the researchers knew they were dealing with some fast pollen-slinging flowers. When the team got hold of a camera that could shoot at 10,000 frames per second, the entire remarkable sequence of events became clear.

Each flower's highly elastic petals flip backward and release springy filaments cocked underneath. Built somewhat like a medieval catapult called a trebuchet, the filaments snap upward, causing pollen to spray from containers hinged to the filaments. The mechanism unfolds so quickly that the pollen experiences 800 times the gravitational force that an astronaut does blasting off in the space shuttle. No other plant motion, such as the snap of a Venus flytrap, comes even close, the researchers report in the May 12 Nature.--S.M.