A member of the daisy family, there are nine varieties of echinacea and they are often collectively known by their common name, purple coneflower.
Echinacea, the purple coneflower, is the best known and researched herb for stimulating the immune system.
Several different varieties of Echinacea may be available form garden supply shops where you live, but if you want to devote a mass planting area to the lovely coneflower, you might need a mail order or Internet source.