| Echinacea | |
|---|---|
 | |
| Echinacea purpurea 'Maxima' | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Subfamily: | Asteroideae |
| Tribe: | Heliantheae |
| Subtribe: | Zinniinae |
| Genus: | Echinacea Moench, 1794 |
| Synonyms | |
Echinacea/ˌɛkɪˈneɪsiə,ˌɛkɪˈneɪʃiə/[1] is agenus ofherbaceousflowering plants in thedaisy family. It has ten species, which are commonly calledconeflowers. They are native only in eastern and centralNorth America, where they grow in wet to dryprairies and open wooded areas. They have large, showyheads of compositeflowers, blooming in summer. The generic name is derived from the Greek wordἐχῖνος (ekhinos), meaning "hedgehog", due to the spiny central disk. These flowering plants and their parts have different uses. Some species are cultivated in gardens for their showy flowers. Two of the species,E. tennesseensis andE. laevigata, were formerly listed in the United States asendangered species;E. tennesseensis has been delisted due to recovery[2] andE. laevigata is now listed as threatened.[3]
Echinacea has a long history of use intraditional medicine byIndigenous peoples for treating infections, pain, and wounds, and it later gained popularity in Western herbal remedies, especially for colds. However,modern research shows weak or inconclusive evidence for its effectiveness, with concerns about product variability and potential side effects. Regulatory authorities have not approvedEchinacea products for any medical use.
Echinacea species areherbaceous,drought-tolerantperennial plants growing up to 140 cm (4 ft 7 in) in height. They grow fromtaproots, exceptE. purpurea, which grows from a shortcaudex with fibrous roots. They have erect stems that in most species are unbranched. Both thebasal and cauline (stem) leaves are arrangedalternately. The leaves are normally hairy with a rough texture, havinguniseriatetrichomes (1–4 rings of cells), but sometimes they lack hairs. The basal leaves and the lower stem leaves havepetioles, and as the leaves progress up the stem thepetioles often decrease in length. The leaf blades in different species may have one, three, or five nerves. Some species have linear tolanceolate leaves, and others haveelliptic- to ovate-shaped leaves; often the leaves decrease in size as they progress up the stems. Leaf bases gradually increase in width away from thepetioles or the bases arerounded to heart shaped. Most species haveleaf margins that areentire, but sometimes they aredentate or serrate.
The flowers are collected together into single roundedheads at the ends of longpeduncles. Theinflorescences have crateriform tohemispheric shaped involucres which are 12–40 mm (0.47–1.57 in) wide. Thephyllaries, orbracts below the flower head, are persistent and number 15–50. The phyllaries are produced in a 2–4 series. The receptacles are hemispheric toconic. Thepaleae (chaffs on the receptacles of manyAsteraceae) have orange to reddish purple ends, and are longer than the disc corollas. The paleae bases partially surrounding thecypselae, and are keeled with theapices abruptly constricted toawn-like tips. Theray florets number 8–21 and thecorollas are dark purple to pale pink, white, or yellow. The tubes of thecorolla are hairless or sparsely hairy, and thelaminae are spreading, reflexed, or drooping in habit andlinear to elliptic or obovate in shape. Theabaxial faces of thelaminae areglabrous or moderately hairy. Theflower heads have typically 200–300 fertile, bisexualdisc florets but some have more. Thecorollas are pinkish, greenish, reddish-purple or yellow and have tubes shorter than the throats. Thepollen is normally yellow in most species, but usually white inE. pallida. The three or four-angledfruits (cypselae), are tan or bicolored with a dark brown band distally. Thepappi are persistent and variously crown-shaped with 0 to 4 or more prominent teeth. x = 11.[4]
Like allmembers of the sunflower family, the flowering structure is a compositeinflorescence, with rose-colored (rarely yellow or white)florets arranged in a prominent, somewhat cone-shapedhead – "cone-shaped" because the petals of the outer ray florets tend to point downward (are reflexed) once theflower head opens, thus forming a cone. Plants are generally long lived, with distinctive flowers. The common name "coneflower" comes from the characteristic center "cone" at the center of the flower head.
The firstEchinacea species were named by European explorers after seeing them in the forests of southeastern North America during the 18th century.[5] ThegenusEchinacea was then formally described byLinnaeus in 1753, and this specimen as one of five species ofRudbeckia,Rudbeckia purpurea.[6][7]Conrad Moench subsequently reclassified it in 1794 as the separate but related genus,Echinacea, with the single speciesEchinacea purpurea,[8][9] so that thebotanical authority is given as (L.) Moench.[10] In 1818,Nuttall, using the original name, described a variety ofRudbeckia purpurea, which he namedRudbeckia purpurea varserotina.[11] In 1836,De Candolle elevated this variety to a species in its own right, asEchinacea serotina (Nutt.) DC, by which time four species of the genusEchinacea were recognised.[12][5]
Historically, there has been much confusion over the taxonomic treatment of the genus, largely due to the ease with which the taxahybridize withintrogression where species ranges overlap, and high morphological variation.[13][14] Furthermore it was discovered that thetype specimen forEchinacea purpurea (L) Moench was not the one originally described by Linnaeus, but rather that described by De Candolle asEchinacea serotina (Nutt.) DC.[5]
Many taxonomic treatments of the genusEchinacea have recorded varying numbers of subordinatetaxa, ranging between 2 and 11.[5] One of the most widely adopted schemes was that of McGregor (1968),[13] which included nine species, of which two,E. angustifolia DC andE. paradoxa (Norton) Britton, were further divided into twovarietals.[9] Treatments that include ten species, differ by the addition ofE. serotina (Nutt.) DC.[15] Alternative classification include with four species and eight subspecies, and two subgenera with four species, has been proposed, based onmorphology alone, but has proved controversial.[14] This recognisedsubgenusEchinacea, with the single speciesE. purpurea, and subgenusPallida, with three species,E. atrorubens,E. laevigata andE. pallida. In this scheme, other taxa are reduced tovariety rank, e.g.E. atrorubens var.neglecta.[7][16] Subsequently, McGregor's classification was preserved in theFlora of North America (2006).[4]
DNA analysis has been applied to determine the number ofEchinacea species, allowing clear distinctions among species based on chemical differences in rootmetabolites. The research concluded that of the 40 genetically diverse populations ofEchinacea studied, there were nine to ten distinct species.[17]
Plants of the World Online gives nine accepted species,[18] andWorld Flora Online gives ten:[19]
These two databases differ in their treatment ofE. serotina(Nutt.) DC., the former considering this as a synonym ofE. purpurea and the latter as a distinct species.
Moench named the genusEchinacea, from the Greek wordἐχῖνος (ekhinos) forhedgehog orsea-urchin, in recognition that in the seed stage, the cone has spiny projections.[9][20]
Echinacea is restricted to North America, east of the Rocky Mountains, and in the Atlantic drainage area, predominantly the Great Plains and central United States and adjacent areas of Canada.[16][5][21] The genus range is fromSaskatchewan in the north to almost theGulf of Mexico in Louisiana and Texas in the south, and from the Ohiooak savannas,glades of Tennessee and the Carolinas in the east, to theRocky Mountain foothills in the west.[15]
Natural populations ofEchinacea are threatened by over-harvesting of wild specimens for the herbal product trade, modification of their habitats by humans, and a decrease in the number of pollinators.[21] Major reductions in the size of populations ofE. laevigata andE. tennesseensis have led to their classification asendangered species.[16][22] Insects and other modes of pollen distribution can be detrimental to conservation efforts.[23]E. tennesseensis had recovered sufficiently by 2011 that it was removed from the list.[24]
Many species ofEchinacea are cultivated for commercial use,[16] while others, notablyE. purpurea,E. angustifolia, andE. pallida, are grown asornamental plants in gardens.[25] Many cultivars exist, and many of them are asexually propagated to keep them true to type.
Echinacea has long been used as atraditional medicine.[16]
Echinacea angustifolia was widely used by theNorth American Indigenous peoples asfolk medicine, with archaeological evidence dating back to the 18th century. Traditional use included external application (insect bites, burns, wounds), chewing of roots (throat and tooth infections) and internal use (cough, pain, snake bites, stomach cramps).[26][27] SomePlains tribes usedEchinacea for cold symptoms. TheKiowa used it for coughs and sore throats, theCheyenne for sore throats, thePawnee for headaches, and many tribes, including theLakota, used it as apain medication.[28] Early European settlers noticed this and began to develop their own uses. According toWallace Sampson, its modern use for thecommon cold began when a Swissherbal supplement maker was told thatEchinacea was used for cold prevention byNative American tribes who lived in the area ofSouth Dakota.[29] The first preparation was Meyers Blood Purifier (c. 1880), which was promoted forneuralgia, rattlesnake bites andrheumatism. By the start of the 20th century it was the most common herbal remedy in America.[citation needed] Commercial cultivation began in Germany in the late 1930s, and in Switzerland in 1950, by A. Vogel. Soon chemists and pharmacologists began the task of identifying potentially active ingredients and their properties. These includedalkylamides,cichoric acid,echinacoside,ketoalkenes andpolysaccharides. Extracts appeared to exhibitimmunostimulant properties and were mainly promoted for the prevention and treatment ofcolds,influenza andsepsis. Despite many different preparations and hundreds of publications, no exact identification of a truly active ingredient has been identified.[26]
According to a 2025 meta-analysis,Echinacea purpurea may reduceupper respiratory tract infection incidence, duration, andantibiotic use in children, with some benefit forotitis media, though safety remains unclear.[30] According to a 2014meta-analysis,Echinacea preparations have not been conclusively shown to effectively prevent or treatcommon colds.[31] According to a 2015meta-analysis,Echinaceaextracts reduce the risk of recurrentrespiratory infections and related complications, especially in susceptible individuals.[32]
When taken by mouth,Echinacea does not usually causeside effects,[33] but may have undesirable interactions with variousdrugs prescribed for diseases, such asheart disease,bleeding, andautoimmune diseases, such asrheumatoid arthritis,lupus, orpsoriasis.[34][35] Although there are no specific case reports ofdrug interactions withEchinacea,[36] safety about takingEchinacea supplements is not well understood, with possibilities that it may cause side effects, such asnausea, stomach upset ordiarrhea, and that it may haveadverse reactions with other medications.[34] One of the most extensive and systematic studies to review the safety ofEchinacea products concluded that overall, "adverse events are rare, mild and reversible," with the most common symptoms being "gastrointestinal and skin-related."[37] Such side effects includenausea,abdominal pain,diarrhea,itch, andrash.[35]Echinacea has also been linked toallergic reactions, includingasthma,shortness of breath, and one case ofanaphylaxis.[37][38][39] Muscle and joint pain has been associated withEchinacea, but it may have been caused by cold orflu symptoms for which theEchinacea products were administered.[37] There are isolated case reports of rare andidiosyncratic reactions includingthrombocytopenic purpura,leucopenia,hepatitis,kidney failure, andatrial fibrillation, although it is not clear that these were due toEchinacea itself.[34] Up to 58 drugs or supplements may interact withEchinacea.[35]
As a matter of manufacturing safety, one investigation by an independent-consumer testing laboratory found that five of eleven selected retailEchinacea products failed quality testing. Four of the failing products contained levels of phenols below the potency level stated on the labels. One failing product was contaminated with lead.[40]
The European Herbal Medicinal Products Committee (HMPC) and the UK Herbal Medicines Advisory Committee (HMAC) recommended against the use ofEchinacea-containing products in children under the age of 12. Manufacturers re-labelled all oralEchinacea products that had product licenses for children with a warning that they should not be given to children under 12 as a precautionary measure.[41]
Although research has not found increased risk ofbirth defects associated with use ofEchinacea during thefirst trimester, it is recommended thatpregnant women should avoidEchinacea products until stronger safety supporting evidence becomes available.[34]
It is recommended that womenbreastfeeding should use caution withEchinacea products due to insufficient safety information available.[34]
The U.S.Food and Drug Administration recommends precaution about usingdietary supplements because some products may not be risk free under certain circumstances or may interact withprescription andover-the-counter medicines.[42]
As with any herbal preparation, individual doses ofEchinacea may vary significantly in chemical composition.[33] Inconsistent process control in manufactured echinacea products may involve poor inter- and intra-batchhomogeneity, species or plant part differences, variable extraction methods, andcontamination oradulteration with other products, leading to potential for substantial product variability.[31][40]
Echinacea products vary widely in composition.[43] They contain different species (E. purpurea,E. angustifolia,E. pallida), different plant segments (roots, flowers,extracts), different preparations (extracts and expressed juice), and different chemical compositions which complicate understanding of a potential effect.[44][45]Well-controlledclinical trials[46] are limited and low in quality, with littlescientific evidence thatEchinaceasupplement products are useful for treating any disease.[35][45][31]
According toCancer Research UK, "There is no scientific evidence to show that echinacea can help treat, prevent or cure cancer in any way. Some therapists have claimed that echinacea can help relieve side effects from cancer treatments such aschemotherapy andradiotherapy, but this has not been proven either."[47]
Although there are multiplescientific reviews andmeta-analyses[48] published on the supposedimmunological effects ofEchinacea, there is significant variability of products used among studies, leading to low-quality or no evidence for efficacy and safety, leading to considerable controversy.[29] Consequently, regulatory authorities, such as the United StatesFood and Drug Administration, have not approvedEchinacea products as safe and effective for any health or therapeutic purpose.[33][35][45]
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