Plant 192

Echinacea species. (Asteraceae)



In 1699, the Keeper of the Oxford Physic Garden, Jacob Bobart the Younger, published an image and description of a spectacular Virginian plant he called 'Dracunculus Virginianus latifolius'. In late seventeenth-century England, this plant was a novelty as seeds were rare; Bobart attributed the plant's introduction to the English clergyman and North American naturalist John Banister (1654-1692). In 1753, the Swedish botanist Carolus Linnaeus cited Bobart's illustration when he formally described the plant; today the plant is known as Echinacea purpurea.

Echinacea is a North American genus of about nine species related to rudbeckias, sunflowers and zinnias. Echinacea species show complex patterns of morphological and genetic variation, compounded by hybridisation among species, making the delimitation of some species difficult.

The distinctive Echinacea flower heads are composed of many tiny flowers in two distinct groups. The flowers around the outside of the head (ray florets) are sterile and have long, strap-like corollas that range in colour from pink to purple; very rarely they are yellow. The flowers on the inside of the head (tube florets) are fertile with symmetrical, dark-coloured corollas and are arranged around a tall, cone-like receptacle. At the base of each of tube florets is a long, stiff, sharp-pointed bract. These bracts give the genus its scientific name, which is derived from the Greek for 'hedgehog'. The common name is a reference to the shape of the receptacle. The insect-pollinated flowers produce dry, indehiscent, single-seeded fruits.

Echinacea species are frequent in the grasslands of eastern North America. They have rosettes of basal leaves, underground stems and deep taproots which enable them to compete effectively with the grasses. Furthermore, these features are also adaptations for coping with the stresses of grassland life, particularly the occurrence of grazers and fire, and the lack of water during the summer months.

Today, three Echinacea species (Echinacea angustifolia, Echinacea pallida, Echinacea purpurea) are frequently grown in gardens. These Echinacea species have also been used in traditional medicines by Native American peoples. A wide range of alternative medicinal products, which claim to alleviate conditions as diverse as the common cold and cancer, are now sold based on Echinacea species. The products on the market are manufactured in a variety of ways, from numerous species harvested from many sources and using different plants parts. The lack of standardisation may contribute to the lack of rigorous clinical evidence supporting the diverse claims implied for these products.

Further reading

Karsch-Völk M et al. 2014. Echinacea for preventing and treating the common cold. Cochrane Database Systematic Review 2: CD000530.

Kindscher K 2016. Echinacea: herbal medicine with a wild history. Springer.

Stephen Harris