Literature about hairy willow-herb is confused. Some authors say the foliage is edible, others warn that it is poisonous. Some admire it for gardens, I would say kill it! It has a long season. Initially the flowers are about an inch across. As the plant grows, the flowers can become smaller, until the last ones are only a quarter that size. Here are some late season flowers near the site for that awful old thicket. They're still lurking around here and there in Ives Fen Preserve, where we do kill them when we find them.