Echinacea is a genus of nine species of flowering plants in the Family Asteraceae, all native to eastern North America.

The genus name is from the Greek echino, meaning "hedgehog", an allusion to the spiny central disk. They are herbaceous, drought-tolerant perennial plants growing to 1 or 2 m in height. The leaves are lanceolate to elliptic, 10-20 cm long and 1.5-10 cm broad. Like all Asteraceae, the flowers are a composite inflorescence, with purple (rarely yellow or white) florets arranged in a prominent, somewhat cone-shaped head; "cone-shaped" because the petals of the outer ray florets tend to point downward (are reflexed) once the flower head opens, thus forming a cone.

The species of Echinacea are:

Echinacea angustifolia - Narrow-leaf Coneflower
Echinacea atrorubens - Topeka Purple Coneflower
Echinacea laevigata - Smooth Coneflower, Smooth Purple Coneflower
Echinacea pallida - Pale Purple Coneflower
Echinacea paradoxa - Yellow Coneflower, Bush's Purple Coneflower
Echinacea purpurea - Purple Coneflower, Eastern Purple Coneflower
Echinacea sanguinea - Sanguin Purple Coneflower
Echinacea simulata - Wavyleaf Purple Coneflower
Echinacea tennesseensis - Tennessee Coneflower

Uses

Some species of Echinacea, notably E. purpurea, E. angustifolia, and E. pallida, are grown as ornamental plants in gardens. It tolerates a wide variety of conditions, maintains attractive foliage throughout the season, and multiplies rapidly. Appropriate species are used in prairie restorations. Some species are used by domestic stock for forage; an abundance of these plants on rangeland supposedly indicates "good health".

Echinacea rhizome was used by North American Plains Indians, perhaps more than most other plants, for various herbal remedies. In the 1930's "Echinacea" became popular in both Europe and America as a folk medicine. Echinacea has been attributed with the ability to boost the body's immune system and ward off infections, particularly the common cold. Depending on which species is used, herbal medicinals can be prepared from the above-ground parts and/or the root. It is not known which of echinacea's many chemical components might be responsible for its touted health benefits, although all species possess compounds of a chemical class called phenols (as do most other plants). Cichoric and caftaric acids are phenols that are present in E. purpurea; echinacoside is a phenol found in higher levels within E. angustifolia and E. pallida roots. When making herbal remedies, these phenols can serve as markers to evaluate the quantity of echinacea in the product. Other constituents that may be important include alkamides and polysaccharides.

A medical study by Taylor et al. (2003) demonstrated that echinacea products made from the entire plant (not just the root), and taken after the second cold symptom appeared, provided no measurable beneficial effect for children in treating the severity or duration of symptoms caused by the common cold virus. Studies by the University of Virginia School of Medicine (Turner, 2005) confirmed these results, and added that Echinacea had no clinically significant effects on the common cold even if taken immediately upon infection, or as a prophylaxis starting a week prior to symptoms of infection. However, a University of Maryland review of available studies concluded that Echinacea, when taken at first sign of a cold, reduced cold symtoms or shortened their duration. This conclusion was based on 13 European studies. The University of Maryland also found that three of four studies concluded that taking Echinacea to prevent a cold was ineffective.[1]

Echinacea herbals should not be taken by persons with progressive systemic and auto-immune disorders such as tuberculosis, leicosis, connective tissue disorders, collagenosis, and related diseases such as lupus erythematosus, according to the German Kommission E. Its use in AIDS or against opportunistic infections in AIDS patients is controversial. If used for more than 8 weeks, Echinacea may cause liver damage (Miller, 1998). It should not be used with other known hepatotoxic drugs such as anabolic steroids, amiodarone (Pacerone® or Cordarone®), methotrexate, or ketoconazole (Nizoral®). Echinacea should also only be taken for a period of up to Eight weeks at a time due to the harmful effects it can have on the liver.