Cirsium undulatum

A widespread and variable thistle. The leaves usually have more strongly undulate margins than those seen below, as the specific epithet indicates.

Pseudanthium near Boyd Sanatorium on the west side of the Organ Mountains, Doña Ana Co., New Mexico, 4 Oct 2009.

A pseudanthium at Aguirre Springs on the east side of the Organ Mountains, Do˜a Ana Co., New Mexico, 2 Oct 2006.

Plant habit at Aguirre Springs, 2 Oct 2006.

An upper cauline leaf at Aguirre Springs, 2 Oct 2006.