Natural distribution map for <b><i><a href="//commons.wikimedia.org/wiki/Category:Alnus_incana" title="Category:Alnus incana">Alnus incana</a></i> ssp. <i>tenuifolia</i></b> — Thinleaf alder.
<ul><li>Native to western North America</li></ul>
Elbert L. Little, Jr., of the U.S. Department of Agriculture, Forest Service, and others
1976
<a rel="nofollow" class="external text" href="https://esp.cr.usgs.gov/data/little/">USGS Geosciences and Environmental Change Science Center: Digital Representations of Tree Species Range Maps from "Atlas of United States Trees" by Elbert L. Little, Jr. (and other publications)</a>