They are native only in eastern and central North America, where they grow in wet to dry prairies and open wooded areas.

The generic name is derived from the Greek word ἐχῖνος (ekhinos), meaning "hedgehog", due to the spiny central disk.

Although commonly sold as a dietary supplement, there is insufficient scientific evidence that Echinacea products are effective or safe for improving health or treating any disease.

The paleae (chaffs on the receptacles of many Asteraceae) have orange to reddish purple ends, and are longer than the disc corollas.

The paleae bases partially surrounding the cypselae, and are keeled with the apices abruptly constricted to awn-like tips.

The tubes of the corolla are hairless or sparsely hairy, and the laminae are spreading, reflexed, or drooping in habit and linear to elliptic or obovate in shape.

[4] Like all members of the sunflower family, the flowering structure is a composite inflorescence, with rose-colored (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.

[12][5] Historically, there has been much confusion over the taxonomic treatment of the genus, largely due to the ease with which the taxa hybridize with introgression where species ranges overlap, and high morphological variation.

[5] One of the most widely adopted schemes was that of McGregor (1968),[13] which included nine species, of which two, E. angustifolia DC and E. paradoxa (Norton) Britton, were further divided into two varietals.

Moench named the genus Echinacea, from the Greek word ἐχῖνος (ekhinos) for hedgehog or sea-urchin, in recognition that in the seed stage, the cone has spiny projections.

[16][5][21] The genus range is from Saskatchewan in the north to almost the Gulf of Mexico in Louisiana and Texas in the south, and from the Ohio oak savannas, glades of Tennessee and the Carolinas in the east, to the Rocky Mountain foothills in the west.

[15] Natural populations of Echinacea are threatened by over-harvesting of wild specimens for the herbal product trade and modification of their habitats by humans.

[23] Many species of Echinacea are cultivated for commercial use,[16] while others, notably E. purpurea, E. angustifolia, and E. pallida, are grown as ornamental plants in gardens.

[16] Echinacea angustifolia was widely used by the North American Indigenous peoples as folk medicine, with archaeological evidence dating back to the 18th century.

Extracts appeared to exhibit immunostimulant properties and were mainly promoted for the prevention and treatment of colds, influenza and sepsis.

[29] A 2015 meta-analysis found tentative evidence that use of Echinacea extracts reduced the risk of repeated respiratory infections.

[32] One of the most extensive and systematic studies to review the safety of Echinacea products concluded that overall, "adverse events are rare, mild and reversible," with the most common symptoms being "gastrointestinal and skin-related.

[35] There are isolated case reports of rare and idiosyncratic reactions including thrombocytopenic purpura, leucopenia, hepatitis, kidney failure, and atrial fibrillation, although it is not clear that these were due to Echinacea itself.

[32] The U.S. Food and Drug Administration recommends precaution about using dietary supplements because some products may not be risk free under certain circumstances or may interact with prescription and over-the-counter medicines.

[42][43] Well-controlled clinical trials[44] are limited and low in quality, with little scientific evidence that Echinacea supplement products are useful for treating any disease.

Some therapists have claimed that echinacea can help relieve side effects from cancer treatments such as chemotherapy and radiotherapy, but this has not been proven either.

[28] Consequently, regulatory authorities, such as the United States Food and Drug Administration, have not approved Echinacea products as safe and effective for any health or therapeutic purpose.