Some of you might recall this photo from the thread http://www.photography.ca/Forums/f11/green-9052.html.



None of us could come up with what it was at the time. Well, a coworker who's a gardener gave me some guesses as to which family it belonged to. Then I got seriously pig-headed. It's tansy mustard. There are two kinds that grow throughout the U. S. and Canada. The first is a European variety, descurainia sophia. It's also called flixweed and common tansy mustard. The second is a native, descurainia pinnata, pinnate tansy mustard. They compete equally well. I'm inclined to think it's the sophia. The pictures of the pinnata seem to be bushier and the flowers fleshier than the examples I've seen. But at least I have a clue now.