Next in the series of posts on composite flowers lacking ray florets is blue mistflower. Like the joe-pye weeds, blue mistflower was once placed in the genus Eupatorium, but nowadays it’s known as Conoclinium coelestinum. The flowers are somewhat similar in appearance to joe-pyes, the heads of tightly clustered disk florets with long protruding styles giving the inflorescences a fine, feathery, misty look.
click on this one to zoom in and see the minute flowers opening on the outside of the heads
Also like joe-pye weeds, blue mistflower likes wet soils; along the banks of the Potomac River, if I see joe-pyes, I’m almost certain to find blue mistflower nearby. Unlike joe-pyes, the plants are short, getting to about two feet tall in ideal conditions.
Speaking of the Potomac, I went back out to check on the spot I reported on last week, a place where in other years I would definitely find mistflower. It was all underwater again. Lots of rain upstream.
Blue mistflower ranges mostly along the Mississippi River basin and its tributaries, from southern Illinois south, and also in the eastern mid-Atlantic and the Carolinas. It’s found in most of Maryland except for the westernmost and easternmost parts of the state.
eastern tailed-blue butterfly (Cupido comyntas) sipping from mistflower
Apparently these flowers are a great nectar source for a variety of butterflies, but I haven’t seen many on it. Three years ago I wrote that I was worried that the blue mistflowers in my garden would become weedy*. “Weedy” is, of course, in the eye of the gardener. They certainly have spread, somewhat aggressively, and I’ve had to pull some out, but they haven’t reached weed status yet.
Elizabeth's Wildflower Blog 
It looks like feral ageratum.
Two feet tall is still a pretty good height. I have worked indirectly with ageratum before, but have never grown it. I like the blue, and I like the fuzzy flowers, so something that looks like sounds appealing, although I doubt it would naturalize in our chaparral climate. I do intend to grow Joe Pye weed though!
It does look a lot like ageratum. Both mistflower and Joe Pye require a fair amount of water.
Joe Pye weed is something that I want to try. It seems to be so common elsewhere. I have never seen it.
beautiful!
and the butterfly too!