Logo IMG
HOME > My Amsci > Restricted Access

Why Leaves Turn Red

Restricted Access The content you've requested is available without charge only to active Sigma Xi members and American Scientist subscribers.

If you are an active member or an individual subscriber, please log in now in order to access this article.

If you are not a member or individual subscriber, you can:


<P>Figure 2. Some senescing autumn leavesClick to Enlarge ImageFigure 1. Anthocyanins . . .Click to Enlarge Image

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.

Connect With Us:

Facebook Icon Sm Twitter Icon Google+ Icon Pinterest Icon RSS Feed

Subscribe to Free eNewsletters!

  • American Scientist Update

  • An early peek at each new issue, with descriptions of feature articles, columns, and more. Every other issue contains links to everything in the latest issue's table of contents.

  • Scientists' Nightstand: Holiday Special!

  • News of book reviews published in American Scientist and around the web, as well as other noteworthy happenings in the world of science books.

    To sign up for automatic emails of the American Scientist Update and Scientists' Nightstand issues, create an online profile, then sign up in the My AmSci area.

Read Past Issues on JSTOR

JSTOR, the online academic archive, contains complete back issues of American Scientist from 1913 (known then as the Sigma Xi Quarterly) through 2005.

The table of contents for each issue is freely available to all users; those with institutional access can read each complete issue.

View the full collection here.

RSS Feed Subscription

Receive notification when new content is posted from the entire website, or choose from the customized feeds available.

Write for American Scientist

Review our submission guidelines.

Subscribe to American Scientist