- Echinacea purpurea a.k.a the Eastern purple coneflower or just Purple coneflower. Echinacea is believed by many people, including me, to stimulate the immune system. A 2007 study by the University of Connecticut combined findings from 14 previously reported trials examining Echinacea and concluded that Echinacea can cut the chances of catching a cold by more than half, and shorten the duration of a cold by an average of 1.4 days. Case closed. Canon 7D, 1/4000 sec @ f/5.6, ISO 200, zoom at 300mm.