Equisetum arvense “Common Horsetail” Equisetaceae

Lolo National Forest, Bitterroot Mountains, MT
May 10, 2015
Robert Niese

Horsetails were once abundant, diverse organisms, but today all surviving members of this ancient clade are restricted to a single genus with a worldwide distribution. This particular stalk is a fertile, strobilus-bearing stem. Their infertile counterparts look almost nothing alike!