Hairy bittercress (Cardamine hirsuta) is a weed you may see at this time of year, said Carol Ann Harlos in WNY Gardening Matters, produced by the Master Gardeners of Cornell Cooperative Extension in Erie County.
This plant and other ephemeral spring weeds pop up when the earth warms, quickly bloom and produce seeds. When the seeds are ripe, they shoot out and wait until autumn to germinate and grow. Depending on the conditions, several generations of plants can occur before the cold weather sets in.
If you are serious about getting rid of this weed you must dig out the taproot because individual plants can regrow from the root.