horsebalm, aka richweed, horseweed, stone root
I’m not sure that there’s anything particularly special or interesting about this plant. It has some medicinal uses. It’s found throughout most of the eastern US and Canada. It’s endangered in Wisconsin. There are three other species of Collinsonia in the US, none of which are found in Maryland. I’m not sure what else to say about it.
Except this: even if it’s supposedly a fairly common plant, I have only ever found one stand of it, which makes it special. There are perhaps three or four plants in this stand, growing atop a boulder alongside Cabin John Creek, almost but not quite above my head.
This makes them tricky to photograph. Because of nearby large vegetation, the plants are always in shade. Since they’re so close to the creek, they’re always being blown around a little. It’s easy to deal with motion or with lack of light, but not both at the same time, especially if you want to zoom in close to see the fascinating little details.
The flowers are quite small.