Contents

15 September 2006
Vol 313, Issue 5793

About The Cover

Cover image expansion

COVER Moonlit silhouette of the North American black cottonwood Populus trichocarpa. Because this tree has a small genome and has long been the subject of commercial and ecological studies, P. trichocarpa was selected as the first woody perennial plant to have its genome sequenced. See page 1596. Photo: David Hiser/Getty Images