University of Tennessee
Forest Resources AgResearch and Education Center
Fall Color Guide

The Geometry of Fall Leaf Color

Leaf Geometry Leaves begin to change color along their outer margins first. These outer edges are the last to get nutrients and water, and as the nutrient supply is decreased, these cells are the first to lose their chlorophyll. The midrib stays green the longest since it gets nutrients first and easiest, and here the chlorophyll can remain active longer.

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University of Tennessee - Forest Resources AgResearch and Education Center
901 South Illinois Avenue, Oak Ridge, Tennessee 37830 · Telephone: 865-483-3571 · Email: UTforest@utk.edu