Desmodium canadense. Perennnial (to zone 4). This native wildflower will grow to 36" tall, pretty much anywhere. It's an unstoppable re-seeder, so let it go in a prairie or wildflower area— the bees and birds will thank you for it. Blooms in the late summer and fall. Seeds need a few months of cold, moist stratification; put your trays in a cold frame or the refrigerator and don't let them dry out.