exuberance

these joyful weeds have been waving at me along the edge of my driveway as i come and go lately. after eight years of STILL blog, i’ve learned the names of most of the plants in my immediate environment, especially the eye-catching ones. but somehow this one has escaped my previous attention. i spent 20 minutes photographing it, and then an hour trying to identify it with no success. any of you recognize this one?

unidentified weed

*the leaves look like they are in the carrot family, but i don’t think it’s wild carrot nor hemlock. the plant is about 18 inches high. it’s growing in the edge of our shady woodlot. and the stem round.