As a comment about
Herb Robert (Geranium robertianum),
Bonehead wrote:
Class B noxious weed in Washington, found in the understory of forests, out-competing natives. It spreads by seed, which can be ejected up to 20 feet from the mother plant. Easy to pull the shallow roots by hand, or can be controlled by mowing prior to seed set. It's a pretty little plant and I was disappointed to discover it is an invasive in my area.