Echinacea purpurea (Purple coneflower)

Echinacea purpurea (L.) Moench

Brauneria purpurea (L.) Britton

Echinacea purpurea (L.) Moench var. arkansana Steyerm.

Rudbeckia purpurea L.

Purple coneflower

Kingdom	Plantae	Plants, but not fungi, lichens, or algae
Subkingdom	Tracheobionta	Vascular plants—plants with a “circulatory system” for delivering water and nutrients
Division	Magnoliophyta	Flowering plants, also known as angiosperms
Class	Magnoliopsida	Dicotyledons—plants with two initial seed leaves
Subclass	Asteridae	A large class that encompasses asters
Order	Asterales	Flowering plants with a central disk flower and surrounding petals, like daisies
Family	Asteraceae	The aster family, which also includes daisies and sunflowers; from the Greek ἀστήρ, “star,” for the star-shaped flowers
Genus	Echinacea	From the Greek word echinos (Εχίνος), ”hedgehog,” because the central disk flower has the spiny look of a hedgehog
Species	purpurea	“Purple”

About plant names...

Purple cornflower is native to eastern North America. The name is derived from the Greek word echinos (Εχίνος), meaning hedgehog, because the central disk flower has the spiny look of a hedgehog.

Plants: 24-54" (60-137 cm) tall and 18-24" (45-60 cm) around, with stems that are usually bristly or hairy.

Leaves: May be alternate or opposite, and may be ovate (sort of egg-shaped with a sharp tip) or more like a grass blade in shape, long and narrow. They are up to 6" (15 cm) × 3" (7.6 cm), with widely spaced teeth and a sandpaper-like feel.

Flowers: These are composite flowers, resembling daisies, 2-5" (5-12 cm) in diameter, with central yellow-brown disk flowers in a flattish or rounded mound, and 10-20 pink-purple ray flower petals. On close inspection, the central disk flowers often have red tips. The ray flowers often droop, accentuating the central disk.

Fruits: The central cone flowers become gray seeds in the fall.

Medical: Echinacea, especially this plant and the closely related Echinacea angustifolia, are wildly popular as immune system stimulants said to reduce the likelihood of getting colds, or to reduce their duration. Many small-scale studies have suggested possible benefits from preparations made from the roots. There is also some evidence that it is helpful in speeding wound recovery. But The National Center for Complementary and Alternative Medicine, part of the National Institutes of Health, says:

A study published in Annals of Internal Medicine in 2010 noted no significant improvements in duration or severity of illnesses in 713 participants.
A study published in the New England Journal of Medicine in 2005 noted “no significant effects” among the 437 study volunteers.
Several other large, well-controlled studies also yielded negative results.

A 1998 study, published in Journal of the American Medical Association and the Archives of Family Medicine, was also negative. So was a 2004 study by the Department of Internal Medicine, Marshfield Clinic, and the Biostatistics and Bioinformatics Core, Marshfield Clinic Research Foundation.

The Physician’s Desk Reference for Herbal Medicines, a tome that attempts to summarize what is really known about herbal medicines, has a large entry for echinacea. The plant contains alkamides, glycoproteins, caffeic acid derivatives, and polysaccharides that may have antibacterial, anti-inflammatory, collagen-protecting, or cytokine stimulation effects. However:

A major 2006 Cochrane Collaboration review of 22 comparison trials concluded that the trials lacked sufficient controls necessary to draw hard conclusions.
A major 2005 structured review evaluated 322 separate studies, finding that only two met 11 criteria designed to measure quality (e.g. double-blinding, quantifiable analysis, compliance testing, and randomized assignment for treatment). The two solidly designed studies did not find evidence echinacea helps in treatment of the common cold.
Results for several specific studies were presented, showing contradictory results for whether echinacea preparations influence recovery times for colds, though there is evidence of some degree of symptom relief.

I don’t believe in unsubstantiated herbal cures. Of course some plants have curative properties; in fact, some of the most poisonous, properly used, can save lives. Foxglove comes to mind, used for digitalis. But taking drugs with unknown properties is, at best, expensive but harmless, and at worst, dangerous. In the case of echinacea, at least it is fairly harmless. However, it should definitely not be used in patients with progressive systemic and autoimmune disorders, for example: tuberculosis, leicosis, connective tissue disorders, collagenosis, or lupus.

Online References:

Echinacea purpurea on Missouriplants.com

Echinacea purpurea at Illinois Wildflowers

Echinacea purpurea at the Ohio State University PLANTFacts database

Echinacea purpurea at the Missouri Botanical Garden

Echinacea purpurea on plants.ces.ncsu.edu

Echinacea purpurea at the Lady Bird Johnson Wildflower Center

Echinacea purpurea on Plants for a Future, a resource and information centre for edible and otherwise useful plants

References:

Multiple Authors, PDR for Herbal Medicines, Thomson Healthcare Inc., 2007, p. 266