Echinacea is a genus of drought-tolerant perennial herbs in the daisy family, Asteraceae, whose nine or ten species go by the name coneflower. They are found only in eastern and central North America, east of the Rocky Mountains, from Saskatchewan almost to the Gulf of Mexico, on wet to dry prairies and in open woodland. The plants reach up to about 140 cm, most from a taproot, with rough and usually hairy leaves. In summer each long stalk ends in a single large head of florets, usually rose-coloured and only rarely yellow or white, set around a raised centre; the outer rays bend downwards as the head opens, which gives the cone of the common name, and the cone's spiny scales gave the genus its name, from the Greek for hedgehog. Grieve describes the flowers of the narrow-leaved species as a rich purple. Linnaeus first placed the plant in Rudbeckia, a name it still carries as a folk name, before Moench gave it a genus of its own in 1794. Indigenous peoples of North America used it as a remedy, chewing the roots and applying it to bites, burns and wounds; modern research finds the evidence for its benefit weak or inconclusive. Harvesting from the wild for the herbal trade threatens natural populations. Cunningham records that American Indians offered it to the spirits to make their spells surer and stronger.