SCIENCE IN THE NEWS DAILY

Why Do Leaves Turn Color in the Fall?

from the Washington Post (Registration Required)

There aren't many things that look their best right before they die, but the leaf of the sugar maple is one of them.

Briefly at the end of each growing season, maple leaves seem to want to imitate the sun, whose energy they've been dutifully collecting all summer. As their green-pigmented chlorophyll breaks down, they glow red and orange in a display more suitable to the exhibitionist tropics than the sober temperate zone. It doesn't last long. In a few weeks they're brown, dry and on the ground.

Until about a decade ago, the autumnal turning of the leaves was viewed by biologists as a pointless if appealing feature in the life history of many deciduous trees. The standard teaching was that the bright colors were lurking in the leaves all along. Only when the chlorophyll disappeared did they become visible, the colorful undergarments in a deathbed striptease. It turns out, though, that's only half true.