Why Leaves Turn Red
The content you've requested is available without charge only to active Sigma Xi members, affiliates and American Scientist subscribers.
If you are an active member, affiliate or individual subscriber, please log in now in order to access this article. Be sure you've entered your member or subscriber number on your profile page.
If you are not a member, affiliate or individual subscriber, you can:
Abstract:
Figure 2. Some senescing autumn leaves" float="LEFT" />
Anthocyanins are plant pigments found in leaves, flowers and fruits. Most strikingly, they color autumn leaves red. Over more than a century, biologists have proposed a variety of hypotheses for why colorful autumn foliage should exist, but experiments over the last decade are finally yielding definitve explanations. Anthocyanins protect leaves from damage in at least two ways—by directly shielding chloroplasts from bright light and by scavenging free radicals. It is less clear why plants expend so much energy to produce these new pigments for leaves that are about to die.