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Name: Lily
Status: student
Grade: 12+
Location: Outside U.S.
Country: China
Date: Summer 2013

Why do some plants have leaves with purple underside? Does this feature bring any evolutionary advantage?

The purple color is related to anthocyanin pigments in the leaf, particularly of shade-plants; however, the actual advantages/benefits seem to remain unclear:

Sincerely, Anthony Brach Anthony R. Brach, Ph.D., Harvard University Herbaria, 22 Divinity Ave., Cambridge, MA 02138

Hi Lily,

Thanks for the questions. The purple underside of a plant may be due to white light shining through the top of the leaf. Some components of the white light may be absorbed so as to leave the purple color--and this is what you see. I am not sure of an evolutionary advantage other than the fact that the plan uses the light that is most abundant.

I hope this helps. Please let me know if you have more questions. Thanks Jeff

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