Colored Leaves and Evolution
Location: Outside U.S.
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:
Anthony R. Brach, Ph.D., Harvard University Herbaria, 22 Divinity Ave., Cambridge, MA 02138
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.
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Update: November 2011