Three Echinacea species are commonly used for medicinal purposes: Echinacea purpurea, Echinacea angustifolia, and Echinacea pallida.
Echinacea is a genus of North American flowering plants in the daisy family, Asteraceae. The plants are commonly called coneflowers because of their raised, spiny central flower disks. Although the genus contains substantially more than three species, herbal products and clinical research have traditionally centered on these three.
Echinacea purpurea is usually called purple coneflower and is widely cultivated. Echinacea angustifolia, or narrow-leaved coneflower, and Echinacea pallida, or pale purple coneflower, are also important medicinal species. Preparations may use roots, leaves, flowers, expressed juice, or extracts, so products labeled simply “echinacea” are not necessarily chemically identical.
The number three refers to the species most commonly used medicinally, not the total number of species in the genus. Depending on the taxonomic treatment, botanists recognize roughly nine or ten Echinacea species. Evidence for echinacea products in treating or preventing colds remains mixed, and the different species and plant parts make comparisons difficult.