Tom's Blog

Thursday, July 24, 2008

The wrong Echinacea

There are two species of Echinacea found in southern Wisconsin, the right one (E. pallida, pale purple coneflower) and the wrong one (E. purpurea, purple coneflower, photo at left). The latter is not native to Wisconsin but has been widely planted in prairie gardens and estates. It is more colorful than the pallid species, and hence favored by those who think that a prairie should be a flower garden rather than a functioning ecosystem. The UW Herbarium considered it to be an "escaped" species.

E. pallida is native to Wisconsin but also restricted in its range. The Herbarium shows it in only 6 of Wisconsin's 72 counties and it is on the Wisconsin DNR Threatened Species list.

We have planted E. pallida widely at Pleasant Valley Conservancy, and it is thriving in all of our planted prairies as well as in most of the savannas. I described this species in my Blog Post of 29 June 2008.

However, the photos in this post of E. purpurea are also from one of our open savanna areas (Unit 11A). If this is the wrong species, what is it doing here? We definitely did not intentionally plant it.

The origin is simple. It was planted at the U.W. Arboretum in the early years of the development of the Curtis Prairie, before the knowledge that this species was not native to Wisconsin. It has spread from there and now "contaminates" seed mixes thought to be E. pallida. The seed heads of E. pallida and E. purpurea look almost the same, and seed collectors are often not cognizant of the difference.

The way you tell the difference is from the leaves. The leaves of E. pallida are narrow whereas those of E. purpurea are wide (see photo to left). This is important because in certain locations the flowers of E. pallida also show intense color. So when collecting seeds of this species, check the leaves before throwing a seed head into the collecting bucket.

Since E. pallida is so widely planted, it is rare to see it growing as a native species. In fact, I have seen it growing that way in only one location, the Swamplovers, Inc. site off County KP west of the Village of Cross Plains. Even there its presence was a surprise. The steep south-facing bluff was cleared of brush about eight years ago and controlled burns were carried out. Almost immediately, E. pallida appeared, and has maintained large populations ever since. It had obviously existed in a suppressed state under all the brush, and thrived once it was brought out into the light. This is a dramatic example of the value of brush removal from potential prairie or savanna sites!

At Pleasant Valley Conservancy we have seen a few specimens of E. purpurea in several of our planted prairies. We usually pull it out after it has finished flowering but before it starts making seeds. Eventually, we should have eradicated this "wrong" species.


Post a Comment

Subscribe to Post Comments [Atom]

<< Home