From <a href="https://en.wikipedia.org/wiki/Eduard_Strasburger" class="extiw" title="en:Eduard Strasburger">Eduard Strasburger</a>, <i>Lerbuch der Botanik</i>.<br><p><a href="https://en.wikipedia.org/wiki/Betula_pubescens" class="extiw" title="en:Betula pubescens"><i>Betula alba</i></a>. 1, Branch with male (a) and female (b) inflorescences; 2, bract with three male flowers; 3, bract with three female flowers; 4, infrutescence; 5, fruit. (After Wossidlo.)<br></p>
<small>Illustration from 1911 Encyclopædia Britannica, article <a href="https://en.wikisource.org/wiki/1911_Encyclop%C3%A6dia_Britannica/Birch" class="extiw" title="s:1911 Encyclopædia Britannica/Birch">Birch</a></small>
Encyclopædia Britannica, 1911
2015-01-27
<a href="https://en.wikipedia.org/wiki/Encyclop%C3%A6dia_Britannica_Eleventh_Edition" class="extiw" title="en:Encyclopædia Britannica Eleventh Edition">Encyclopædia Britannica Eleventh Edition, Vol. 3, Page 958</a> <a href="//commons.wikimedia.org/w/index.php?title=File:EB1911_-_Volume_03.djvu&amp;page=981" class="image"><img alt="EB1911 - Volume 03.djvu" src="https://upload.wikimedia.org/wikipedia/commons/thumb/c/c8/EB1911_-_Volume_03.djvu/page981-100px-EB1911_-_Volume_03.djvu.jpg" decoding="async" width="100" height="136" srcset="https://upload.wikimedia.org/wikipedia/commons/thumb/c/c8/EB1911_-_Volume_03.djvu/page981-150px-EB1911_-_Volume_03.djvu.jpg 1.5x, https://upload.wikimedia.org/wikipedia/commons/thumb/c/c8/EB1911_-_Volume_03.djvu/page981-200px-EB1911_-_Volume_03.djvu.jpg 2x" data-file-width="1984" data-file-height="1991"></a>