10. Dog-strangling vine (Cynanchum louiseae)
Also known as swallowwort, dog-strangling vine is a herbaceous perennial vine that can grow from one to two metres in height by twining and climbing onto trees. As the vine climbs, it essentially strangles its host. Although it prefers sunny fields, it can grow quite well in shaded woods and forests. In late June, the vine produces small pink flower clusters that develop into fruit. These long pods contain numerous fluffy white seeds that scatter in the wind in late August. Aside from propagating by seed, dog-strangling vine also has an extensive root system that enables it to resprout, after the vine has been cut. The vine belongs to the milkweed family and often monarch butterflies confuse dog-strangling vine for milkweed. Any larvae that hatch from eggs laid on the leaves of the vine often die.