Tom's Blog

Friday, August 22, 2008

Hyssops in the savannas

This is the time when the hyssops are in full bloom. We have two species at Pleasant Valley Conservancy, giant yellow hyssop (Agastache nepetoides; photo to the left), which is Threatened, and giant purple hyssop (Agastache scrophulariaefolia), which I guess is more common since it is not listed. Both are in the mint family and have similar flower characteristics.

Ten years ago we started out with neither of these plants, but had good seed sources. The giant yellow thrived right away and we had it in most of our savannas, but especially in the upper bur oak savannas. For several years, we only had one or two plants of purple hyssop, but it has gradually spread, and now I think we have more purple than yellow.

The area I found them in yesterday was an opening in a fairly wooded area. There is a knoll here due to a small outcrop of the Prairie du Chien dolomite, and it formerly had a lot of nasty burdock. (You know burdock, I'm sure. It makes these large burs that stick tight to your clothing.) We have been controlling the burdock here for five or six years, with the herbicide 2,4-D, and this year we must have gotten everything right, because it is now all gone and has been replaced by the two hyssops.

The word "giant" in their common names is pretty accurate. They stand quite tall, and in fact I could see this patch from a long way off, and plowed my way through all the tick trefoil so that I could take these photos. Actually, my photos don't do justice to the size of these plants, because they are so large that they are hard to photograph well. I decided to focus in on the flowers, themselves.

As the photos show, these aren't the showiest plants in the savanna. The colors are subdued, and I hardly think "purple" is the correct word for this one. Perhaps lavender would be better?


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