Elkweed

Other Names

American columbodeer earsdeer's earsdeertongueelk weedFrasera angustifoliaFrasera caroliniensisFrasera macrophyllaFrasera officinalisFrasera speciosaFrasera speciosa var. angustifoliaFrasera speciosa var. stenosepalaFrasera stenosepalaFrasera verticillataFrasera walterigiant fraseragiant swertiagreen gentianmonument plantshowy fraserashowy green-gentianSwertia carolinensisSwertia caroliniensisSwertia fraseraSwertia radiataSwertia radiata var. macrophyllaTesseranthium angustifoliumTesseranthium macrophyllumTesseranthium radiatumturret plant

Synopsis

Elkweed (Frasera spp.): A Comprehensive Reference

1. Identity, Taxonomy, and Botanical Description

1.1 Primary Species and Nomenclature

The common name elkweed is applied most frequently to two closely related North American members of the gentian family. Frasera speciosa is a species of flowering plant in the gentian family (Gentianaceae) known by the common names elkweed, monument plant, and green gentian. The eastern counterpart, Frasera caroliniensis, commonly known as American columbo or yellow gentian, is a herbaceous perennial of the gentian family Gentianaceae found in the deciduous forest of Southern Ontario and throughout the eastern and southeastern United States. A third species, Frasera albomarginata, commonly known as Desert Elkweed, is found in the southwest deserts of the United States, including the California desert as well as Nevada. A fourth species, Frasera paniculata, is known as Tufted elkweed.

The accepted botanical name for the western elkweed is Frasera speciosa, with synonyms including Frasera angustifolia, F. macrophylla, F. stenosepala, and Swertia radiata (Kuntze). The eastern species, F. caroliniensis, was previously known as Swertia caroliniensis. The genus name Frasera honors a specific botanical figure: the genus name, Frasera, was coined by Thomas Walter in 1788 in honor of the plant collector John Fraser.

1.2 Common Names

Common names for Frasera speciosa include Green Gentian, Elkweed, Deer's Ears, and Monument Plant.
Frasera caroliniensis is known as American Columbo, Yellow Gentian, and Green Gentian. It is called American Columbo from the resemblance of the root, when cut into transverse slices and dried, to the foreign columbo, and from the similarity of its medical properties.
Frasera albomarginata is commonly known as Desert Elkweed.

1.3 Morphology and Botanical Description

Frasera speciosa is a biennial/perennial herb growing from a woody base surrounded by rosettes of large leaves that measure up to 50 centimeters long by 15 wide. It produces a single erect stem which can reach two meters in height. The stem bears whorls of lance-shaped, pointed leaves smaller than those at the base. The plant is monocarpic, growing for several years and only flowering once before it dies.

Elkweed is a robust and showy plant. The flower stalk, growing up to 8 feet tall, erupts from a very large basal rosette of leaves. It flowers only once in its lifetime of 20 to 80 years and then dies. Blooming produces about 600 flowers per plant and about 60 seeds per flower.

The basal leaves are green with a waxy coating (glaucous) and 7–50 centimeters long and 1–15 centimeters wide. The plant is a perennial herb from an unbranched, woody base, with a single stem 1–2 m tall, glabrous or scabrous-puberulent throughout.

This plant demonstrates mast flowering, where plants of different ages in a given mountain meadow may all flower synchronously due to auspicious combinations of environmental stimuli.

The eastern species, F. caroliniensis, is similarly dramatic: American columbo is a monocarpic perennial, meaning it flowers once after multiple seasons, and then dies. When it reaches the flowering stage, the 3–6 inch lanceolate leaves develop (usually in whorls of four) on a round elongated stem, and approximately 50 to 100 flowers will develop a panicle, with the fruits maturing soon after.

1.4 Geographic Range and Habitat

Frasera speciosa is native to sunny, grassy meadows and mountainsides of the western US and the Rocky Mountain states south into Mexico. It is native to western North America — California to Washington — and grows on dryish or dampish places, in rich soils in open pine woods, aspen groves, etc., at 1500–3000 metres elevation.

Frasera caroliniensis ranges across Michigan, Illinois, Indiana, Ohio, Pennsylvania, New York, Missouri, Arkansas, Oklahoma, and all states south of the Ohio River and east of the Mississippi River (except West Virginia and Florida); and in Canada: Ontario. It grows in rich forests and deciduous, ± open woods, often ravines and upper slopes of cove forests, over mafic or calcareous rocks, and floodplain forests.

Elkweed grows in soils comprised of acidic decomposed organic matter, found in the rich soils of open pine forest, aspen groves, etc. It prefers sandy and loamy soils and requires well-drained soil.

1.5 Conservation Status

The eastern species carries significant conservation concern. Frasera caroliniensis is listed as a species of special concern in Canada by SARA (Species at Risk Act), as threatened in New York, and as endangered in Pennsylvania. This species is endangered in Ontario and nationally in Canada. The most extreme limiting factor for this species is invasive plants that are heavily infesting its habitat. This may be attributed to its long life cycle, which would not allow the species to adapt to rapid changes in the environment, and therefore not survive long enough to disperse its seeds. Its Canadian conservation status was designated Special Concern in April 1993 and re-examined and designated Endangered in April 2006.

Frasera caroliniensis is considered rare or threatened in parts of its range, largely due to habitat loss and its extremely slow reproductive cycle. These conservation concerns have practical implications for commercial or wild-harvest use of the eastern species.

2. Traditional and Historical Use

2.1 Native American Ethnobotanical Use

Elkweed has a well-documented history of medicinal use by indigenous peoples of North America. American Columbo (F. caroliniensis) was used for a wide range of medicinal purposes by the Cherokee Nation, including as a tonic, antidiarrheal, antiemetic, and a disinfectant. Cherokee applications of the root are documented to include treatment of dysentery: the root was used to treat dysentery.

For Frasera speciosa, the western elkweed, Native American applications spanned multiple systems. The whole plant is febrifuge, pectoral, laxative, and tonic. An infusion of the dried, powdered leaves, or the root, has been used in the treatment of diarrhea. A cooled decoction of the roots has been used in the treatments of asthma, colds, and digestive complaints. An infusion of the plant has been used as a contraceptive.

The root, when ground into a powder and then mixed with oil, has been used as a parasiticide in order to kill lice.

The most common use of Desert Elkweed (Frasera albomarginata) medicinally was to use the root as an eyewash to soothe sore eyes.

2.2 Eclectic and 19th-Century Medical Use

The dried root of Frasera caroliniensis, which was official in the United States Pharmacopoeia from 1820 to 1880, is used as a simple tonic. This formal recognition underscores how seriously it was regarded by the medical establishment of that era. This indigenous plant, found in most of the Southern and South-western States, may be used in many instances with equal benefit to that derived from Cocculus palmatus — Columbo.

From an 1860 account of Eclectic physician Dr. Charles A. Lee, published in the Journal of Materia Medica and archived at PubMed/PMC: the root when freshly dug is both emetic and cathartic, in this respect resembling most of our indigenous tonics. When carefully dried, it is a mild tonic, fulfilling the same indications as the other simple bitters. According to some writers, it combines laxative with its tonic properties, in this respect resembling rhubarb, while its sweetish bitter taste reminds us of gentian.

In atonic affections of the digestive organs, the cold infusion proved a serviceable remedy. Raffinesque states that its internal and external use cured extensive gangrene of the lower extremities when bark had failed; also, that it proved successful in intermittents, and was greatly used in the western states in fevers, colics, griping, nausea, and diarrhea. More extravagant historical claims included: it was a common belief in the early 19th century that the root of the plant might be externally used for gangrene. It was also claimed to be useful in treating jaundice, scurvy, gout, and rabies. Medicinal uses for American columbo have mostly been rebutted.

A teaspoonful of the powdered fresh root, in hot sweetened water, acted as a very prompt emetic. In the Eclectic medical tradition, the root is among the reliable tonics, with relaxing and gently stimulating properties first manifested, and leaving behind a mild and pleasant astringent impression.

2.3 Preparations Documented in the Historical Record

The Eclectic physician's materia medica described multiple pharmaceutical preparations, documented in historical records now archived at PMC:

Decoction: One ounce of crushed frasera, digested for half an hour in a quart of boiling water, strained, and then evaporated till a pint remains, forms an excellent decoction. Half a fluid ounce may be given three or four times a day.
Solid Extract: The solid extract, made from the watery decoction, is a good concentrated form in which to exhibit this article. The dose may range from three to eight grains.
Fluid Extract: To make this preparation, a pound of crushed frasera may be treated in the percolator with diluted alcohol till eight fluid ounces have passed; then treated with water till all the strength of the drug is obtained; the latter product evaporated to eight fluid ounces, and then added to the first product. Dose, half a fluid drachm.

In traditional medicine contexts more broadly, the fresh or dried leaves and root are used in traditional medicine in tea or tincture form as a digestive bitter promoting gastric secretions, treats indigestion, poor food assimilation, and constipation.

The powdered plant is applied externally to ulcers as a poultice.

2.4 Harvest Timing

The root is used in the treatment of dysentery, stomach complaints, and a lack of appetite. It should be harvested in the autumn of its second year, or the spring of its third year.

3. Key Chemical Constituents and Phytochemistry

3.1 Xanthones

The Frasera genus, as a member of Gentianaceae, is notable for its rich xanthone content. Xanthones from higher plants appear to be associated mainly with the families Clusiaceae (55 species in 12 genera) and Gentianaceae (28 species in 8 genera). The genus Frasera is explicitly identified as a xanthone-containing plant: some of the plants, ferns, and fungus species which contain xanthones include Frasera (among others in the Gentianaceae).

Rigorous phytochemical work on F. caroliniensis roots has revealed a complex xanthone profile. Phytochemical investigation of F. caroliniensis roots resulted in the isolation of 25 xanthones and three secoiridoids, the structure of which was elucidated by spectroscopic means (NMR, MS, and UV).

The specific xanthones identified from F. caroliniensis root in the Cherokee ethnobotany phytochemistry literature include: 1-hydroxy-2,3,4,7-tetramethoxyxanthone, 1-hydroxy-2,3,4,5-tetramethoxyxanthone, 1-hydroxy-2,3,7-trimethoxyxanthone, 1-hydroxy-2,3,5-trimethoxyxanthone, swerchirin, and 1,3-dihydroxy-4,5-dimethoxyxanthone.

3.2 Secoiridoids and Iridoids

Alongside xanthones, the Gentianaceae family is characterized by bitter secoiridoid glycosides. A validated analytical study specifically including Frasera caroliniensis detected both classes: the iridoid loganic acid, four secoiridoids, and 29 xanthones were separated on a RP-18 column using aqueous o-phosphoric acid and acetonitrile as mobile phase. Phytochemical investigation of F. caroliniensis roots resulted in isolation of 25 xanthones and three secoiridoids.

Secoiridoidal and iridoid glycosides such as gentiopicroside, xanthones, monoterpene alkaloids, polyphenols, and flavones are the constituents that have been shown to have pharmacological activities in different gentian species. These compounds are directly responsible for the characteristic bitter taste of elkweed: the bitter-tasting secoiridoid glucoside gentiopicroside (gentiopicrin, GPS) occurs mainly in the Gentianales order, in the botanical family Gentianaceae.

3.3 Stability of Constituents

Stability of the key compounds is relevant to preparation and storage. After six months of storage, decomposition of gentiopicroside and sweroside was observed. The swertiamarin content was nearly unchanged when stored at room temperature or in the refrigerator, but high temperature conditions reduced the content to 85%. In contrast, xanthones were stable under long-term, refrigerated, and accelerated conditions.

4. Mechanisms of Action

4.1 Bitter Tonic and Digestive Mechanisms

The primary mechanism through which dried elkweed root has traditionally been used — and which has the most parallels in modern science — is as a bitter tonic. When dried, it is a simple bitter that can be used as a digestive tonic in a similar way to gentian root (Gentiana spp.), but the fresh root is cathartic and emetic. The mechanism of bitter tonics in the Gentianaceae family is understood to involve stimulation of bitter receptors (TAS2Rs) in the gastrointestinal tract, which reflexively increase gastric secretions, bile flow, and digestive enzyme output. Secoiridoids such as gentiopicroside and swertiamarin, the same classes isolated from F. caroliniensis, are responsible for these actions in well-studied relatives.

Amarogentin and amaroswerin have the strongest gastroprotective effects among the other secoiridoids. Gentiopicrin and xanthone isogentisin, mangiferin from leaves and flowers, have considerable antimicrobial activities. The hepatoprotective activities are related to sweroside, swertiamarin, and gentiopicrin. These findings are from studies on closely related gentian-family species and are relevant as a framework for understanding elkweed constituents, though direct studies on Frasera-specific preparations are largely absent.

4.2 Xanthone-Mediated Anti-Proliferative Activity

The most directly Frasera-specific mechanistic finding in the peer-reviewed literature concerns vascular smooth muscle cell (VSMC) proliferation inhibition. Aberrant proliferation of vascular smooth muscle cells (VSMC) plays a major role in restenosis, the pathological re-narrowing of the blood vessel lumen after surgical treatment of stenosis. Since available anti-proliferative pharmaceuticals produce unfavorable side effects, there is high demand for the identification of novel VSMC proliferation inhibitors.

A natural product screening approach using a resazurin conversion assay enabled the identification of gentisin from Gentiana lutea as a novel inhibitor of VSMC proliferation with an IC50 value of 7.84 µM. Aiming to identify further anti-proliferative compounds, 13 additional nonprenylated xanthones, isolated from different plant species, were also tested. While some compounds showed no or moderate activity at 30 µM, 1-hydroxy-2,3,4,5-tetramethoxyxanthone, swerchirin, and methylswertianin showed IC50 values between 10.2 and 12.5 µM.

The anti-proliferative effect was confirmed by the quantification of DNA synthesis (BrdU incorporation) in VSMC. Cell death quantification (determined by LDH release in the culture medium) revealed that the compounds are not cytotoxic in the investigated concentration range. In conclusion, nonprenylated xanthones are identified as novel, non-toxic VSMC proliferation inhibitors, which might contribute to the development of new therapeutic applications to combat restenosis.

These xanthones — including swerchirin and 1-hydroxy-2,3,4,5-tetramethoxyxanthone — are specifically among those isolated from Frasera caroliniensis roots, as confirmed by the same research group.

5. Scientific Evidence by Area of Use

5.1 Digestive System

Traditional claim: Elkweed root as a bitter digestive tonic, treatment for dysentery, stomach complaints, indigestion, and lack of appetite.

Scientific evidence: There are no clinical (human) trials of Frasera preparations for any digestive indication. The closest scientific support comes from in vitro and animal work on related Gentianaceae species sharing the same bitter secoiridoid constituents. Gastroprotective effects have been demonstrated for Gentianaceae secoiridoids including gentiopicrin, amarogentin, and amaroswerin in related species. The root of F. caroliniensis is reported as cathartic, emetic, stimulant, and tonic. No controlled human studies exist for elkweed's digestive effects specifically.

Evidence strength: Preliminary; traditional and in vitro only; no clinical trials.

5.2 Vascular and Cardiovascular System

Research context: This is the area where the most direct, peer-reviewed bench science involving F. caroliniensis constituents has been published. A 2015 study published in Molecules (a peer-reviewed MDPI journal, PubMed indexed, PMID 26580586) tested nonprenylated xanthones isolated from Gentiana lutea, Frasera caroliniensis, and Centaurium erythraea.

Compounds including 1-hydroxy-2,3,4,5-tetramethoxyxanthone, swerchirin, and methylswertianin showed IC50 values between 10.2 and 12.5 µM. The anti-proliferative effect was confirmed by the quantification of DNA synthesis (BrdU incorporation) in VSMC. Cell death quantification revealed that the compounds are not cytotoxic in the investigated concentration range. In conclusion, nonprenylated xanthones are identified as novel, non-toxic VSMC proliferation inhibitors, which might contribute to the development of new therapeutic applications to combat restenosis.

Limitations: This is in vitro cell culture research only. No animal studies or human clinical trials have been published. The therapeutic relevance to living organisms is unknown.

Evidence strength: In vitro only; preliminary; no in vivo or clinical data.

5.3 Respiratory System

Traditional claim: Decoctions of roots used for asthma, colds, and respiratory ailments; historical use as an expectorant.

A cooled decoction of the roots has been used in the treatments of asthma, colds, digestive complaints, etc. No peer-reviewed clinical or preclinical studies specifically investigating elkweed's effects on respiratory conditions could be identified.

Evidence strength: Traditional use only; no scientific evidence.

5.4 Fever and Anti-Infective Applications

Traditional claim: The whole plant has been described as febrifuge (fever-reducing). The whole plant is described as febrifuge, pectoral, laxative, and tonic. Frasera caroliniensis (elkweed) has been described as a cholagogue, febrifuge, refrigerant, stomachic, and tonic, used for indigestion, stomachache, heartburn, and catarrhal gastritis, and as a bloodbuilder due to its tendency to raise the white blood cell count. This last claim (raising white blood cell count) appears in a product label cited in an FDA warning letter and has no independent scientific verification identified in the peer-reviewed literature.

Evidence strength: Traditional use only; no clinical evidence; blood cell count claim unverified.

5.5 Topical and Wound-Healing Applications

Traditional claim: External use on wounds, ulcers, and skin irritations. The powdered plant is applied externally to ulcers as a poultice.

Evidence strength: Traditional use only; no peer-reviewed clinical or experimental evidence identified.

5.6 Reproductive/Contraceptive Use

An infusion of the plant has been used as a contraceptive. No scientific studies have investigated this use.

Evidence strength: Traditional use only; no scientific evidence.

6. Body Systems and Health Areas Associated with Elkweed

Based on documented traditional uses and the limited available phytochemical research, elkweed has been associated with the following body systems and health areas:

Gastrointestinal system: Digestive tonic, dysentery, stomachache, indigestion, heartburn, diarrhea, constipation, lack of appetite (traditional use; in vitro analogy from related species)
Liver and gallbladder: Cholagogue (bile-stimulating) use historically recorded; parallel supported by secoiridoid research in related genera
Respiratory system: Asthma, colds, bronchial complaints (traditional use only)
Cardiovascular system: VSMC proliferation inhibition by isolated xanthones (in vitro preclinical research)
Immune system: Historically listed as a disinfectant and claimed bloodbuilder (traditional use; no clinical evidence)
Skin and wounds: Topical poultice for ulcers, bruises, cuts, and abrasions (traditional use only)
Fever management: Febrifuge (traditional use only)

7. Preparations and Dosage Forms

7.1 Forms

Elkweed has been prepared and used in several forms, all documented in historical or ethnobotanical records:

Infusion (tea): An infusion of the dried, powdered leaves, or the root, has been used in the treatment of diarrhea.
Decoction: A cooled decoction of the roots has been used in the treatments of asthma, colds, and digestive complaints.
Tincture: The fresh or dried leaves and root are used in traditional medicine in tea or tincture form.
Solid extract: A concentrated form prepared from watery decoction as described in the 19th-century Eclectic tradition.
Fluid extract: Prepared using diluted alcohol percolation as described above.
Powder/Poultice: The powdered plant is applied externally to ulcers as a poultice.
Oil preparation: The root, when ground into a powder and then mixed with oil, has been used as a parasiticide in order to kill lice.

7.2 Dosages Reported in Historical Sources

The following dosages are reported in primary historical or Eclectic medical sources only; they are not derived from modern clinical trials, which do not exist for elkweed:

Decoction: One ounce of crushed frasera digested in a quart of boiling water, reduced to a pint; half a fluid ounce given three or four times a day.
Solid Extract: Three to eight grains per dose.
Fluid Extract: Dose of half a fluid drachm.
Emetic dose (fresh root powder): A teaspoonful of the powdered fresh root in hot sweetened water acts as a very prompt emetic.

No modern standardized dosing recommendations exist, and no clinical trials have established safe or effective doses for any specific indication.

8. Safety, Toxicity, and Notable Interactions

8.1 Emetic and Cathartic Risk of Fresh Root

The most consistently documented safety concern with elkweed is the distinction between the fresh root and the dried root. The root when freshly dug is both emetic and cathartic. When carefully dried, it is a mild tonic, fulfilling the same indications as the other simple bitters. This sharp pharmacological difference has been confirmed repeatedly across historical and ethnobotanical sources: when dried, it is a simple bitter that can be used as a digestive tonic in a similar way to gentian root (Gentiana spp.), but the fresh root is cathartic and emetic.

8.2 Edibility Caution

It has been reported that North American Indians ate the fleshy root of this plant, but caution is advised since the roots of closely related plants are used medicinally as emetics and cathartics.

8.3 Conservation-Related Harvesting Concern

Frasera caroliniensis is endangered in Ontario and nationally in Canada. The most extreme limiting factor for this species is invasive plants that are heavily infesting its habitat. Wild harvesting of this species therefore carries ecological concerns beyond individual safety, as it could contribute to depletion of already-threatened populations.

8.4 Absence of Modern Toxicological Data

No formal toxicology studies, no long-term safety data, and no drug interaction studies have been conducted on Frasera preparations in human subjects. The in vitro xanthone study specifically noted that the isolated compounds were not cytotoxic in the investigated concentration range, which is a finding limited to cell culture and cannot be extrapolated to oral consumption safety.

8.5 Regulatory Context

The use of Frasera caroliniensis (elkweed) as a dietary supplement ingredient has drawn regulatory attention in the United States. In a 2022 FDA warning letter to a dietary supplement company, the FDA cited product labeling claims for elkweed, noting that Frasera caroliniensis (elkweed) was described as a cholagogue, febrifuge, refrigerant, stomachic, and tonic, used for indigestion, stomachache, heartburn, and catarrhal gastritis, and as a bloodbuilder due to its tendency to raise the white blood cell count, in a context where the FDA objected to labeling and formulation compliance issues.

8.6 Absence from Major Regulatory Monographs

Elkweed (Frasera spp.) does not appear in WHO herbal monographs, ESCOP monographs, the German Commission E monographs, or current European Pharmacopoeia listings. It is not assessed by NIH's National Center for Complementary and Integrative Health (NCCIH) or the NIH Office of Dietary Supplements. This absence reflects the current state of the scientific literature: there is not yet sufficient clinical evidence to support formal regulatory evaluation or monograph development.

9. Overall Assessment of Evidence

Elkweed occupies a well-defined place in North American ethnobotany, with consistent records of use by multiple indigenous nations and a documented entry in the U.S. Pharmacopoeia from 1820 to 1880. Its phytochemistry has been characterized to a meaningful degree, with 25 xanthones and three secoiridoids isolated from F. caroliniensis roots using rigorous HPLC and LC-MS methodologies. Some of its constituent xanthones — shared with better-studied Gentianaceae relatives — have demonstrated biologically interesting properties in in vitro cell culture systems, particularly the inhibition of vascular smooth muscle cell proliferation.

However, the gap between this phytochemical and in vitro foundation and evidence for clinically relevant effects in humans is very large. No randomized controlled trials, no prospective cohort studies, and no formal pharmacokinetic studies of elkweed preparations in humans have been published. All mechanistic inferences are derived either from traditional use records or from in vitro studies. The evidence base for elkweed as a dietary supplement or therapeutic agent remains preliminary and primarily ethnobotanical in character.

References

Health Conditions

Health conditions that Elkweed may help support.

No conditions available.

Body Systems

Body systems that Elkweed may help support.

No body systems available.