Thistle Misidentification

Thistles are amazing flowers, but there are both native and nonnative invasive species in the Western US.  Some people who try to do good by removing nonnative thistles accidentally kill the native species as well. 

NM Thistle, Cirsium neomexicanum. My photo on iNaturalist. Link: https://www.inaturalist.org/observations/15024423

I worked with an AmeriCorps crew in the Sacramento Mountains (Lincoln NF) that had been removing musk thistles.  But I found out they didn’t know how to tell the difference between native and invasive thistles. 

Photo of musk thistle Carduus nutans from iNaturalist user c-guinan. Link: https://www.inaturalist.org/observations/132367683

Even worse, they didn’t even know that there is an Endangered species of native thistle in those mountains!  We investigated and it looks like they at least didn’t kill any endangered thistles, but it could have been really bad. 

 

Photo of Endangered Sacremento Mountains Thistle Cirsium vinaceum from iNaturalist user ck2az.  Link: https://www.inaturalist.org/observations/14433149

I’m currently trying to find the volunteers on the Prescott national forest who are pulling up all of the Arizona thistle along popular trails.  Its especially troubling to me when people who are trying to do good by removing invasive species end up destroying native species.

Arizona Thistle Cirsium arizonicum.  My photo on iNaturalist.  Link:  https://www.inaturalist.org/observations/87880049

Everyone who’s done natural resource work has stories of project missteps.  I don’t know how to prevent all mishaps, but talking about these misidentifications is a good first step.

The NM Native Plant Society has a great Thistle ID book written by Bob Sivinski.