Bai Mao Gen
StarImperata cylindrica
Synonyms: Imperata filifolia, Imperata arundinacea var. pedicellata, Imperata sieberi, Imperata koenigii, Imperata angolensis, Imperata cylindrica var. major, Imperata arundinacea var. indica, Saccharum laguroides, Imperata cylindrica var. africana, Imperata arundinacea var. africana, Imperata arundinacea var. europaea, Imperata cylindrica var. koenigii, Imperata robustior, Saccharum cylindricum, Imperata praecoquis, Imperata cylindrica var. pedicellata, Imperata latifolia, Saccharum negrosense, Imperata arundinacea var. thunbergii, Imperata cylindrica subsp. koenigii, Saccharum sisca, Imperata cylindrica var. thunbergii, Imperata sisca, Imperata arundinacea var. glabrescens, Imperata cylindrica f. pallida, Imperata allang, Imperata arundinacea, Lagurus cylindricus, Imperata dinteri, Imperata koenigii var. major, Saccharum thunbergii, Imperata arundinacea var. koenigii, Calamagrostis lagurus, Imperata cylindrica subvar. koenigii, Saccharum koenigii, Saccharum europaeum, Imperata cylindrica var. latifolia, Imperata thunbergii, Imperata pedicellata, Imperata cylindrica var. europaea, Imperata arundinacea var. latifolia, Saccharum diandrum, Saccharum alopecurus, Imperata ramosa, Imperata cylindrica var. parviflora, Imperata laguroides, Arundo epigeios, Saccharum indum
Traditionally used for
- Nose & throat
- Cough & breathing
- Colds & fever
- Digestion
- Urinary & fluids
☯ TCM Properties
Cools the Blood and stops bleeding; Clears Heat and promotes urination; Clears Heat from the Stomach and Lungs
Traditional Chinese Uses
Bai Mao Gen (woolly grass rhizome) is a sweet, cold herb that cools the Blood and stops bleeding while also clearing Stomach and Lung Heat and promoting urination. It is applied for Blood Heat bleeding conditions including nosebleeds, blood in the urine, and coughing up blood, as well as for fever-induced thirst, nausea from Stomach Heat, and edema from urinary difficulty. Its pleasant taste and gentle action make it one of the most suitable blood-cooling herbs for use as a daily medicinal tea or beverage.
Western Herbalism Properties
Pharmacological Effects
- Diuretic: Oral decoction/aqueous extract induced diuresis in normal rabbits, strongest after 5-10 days; abolished by renal denervation; also linked to the herb's potassium content.
- Coagulant: Powder reportedly shortened recalcification time of rabbit plasma, but result unconvincing given the herb's high calcium content.
- Effect on myocardial 86Rb uptake: IP water-ethanol extract 0.2 ml/10 g increased mouse myocardial 86Rb uptake by 47.4% versus control.
Source: Zhu YP. Chinese Materia Medica: Chemistry, Pharmacology and Applications. Harwood Academic, 1998, p. 410.
Relationships
Full-screen graph →Click a node for details · double-click to expand it · Ctrl/⌘ + scroll or two fingers to zoom and pan.
Gallery
Botanical Description
Imperata cylindrica is a perennial grass growing 0.3-1.5 m tall from an extensive network of creeping rhizomes. Leaves are flat, erect, linear, 20-120 cm long and 3-18 mm wide, with sharp, cutting edges and a prominent midrib. The inflorescence is a cylindrical, silky white, feathery spike 5-20 cm long due to long, silky, silver-white hairs on the spikelets. The rhizomes are slender, white to yellowish, and penetrate deeply into soil. In TCM, the dried rhizomes (Bai Mao Gen) are used, sweet-tasting when fresh.
Open, disturbed habitats, grasslands, roadsides, forest clearings, and degraded land; native to tropical and subtropical regions of Africa, Asia, Australia, and southern Europe; one of the most widespread grasses in the world.
Imperata cylindrica is one of the most problematic invasive grasses worldwide, classified as one of the ten worst weeds in the world. It has colonized large areas of disturbed land throughout tropical regions. No conservation concerns; the concern is rather about its invasive spread.
Active Constituents
Cylindrin
Triterpene (arborane-type)One of the characteristic pentacyclic triterpenes of the rhizome and among the first compounds isolated from this drug. It is used as a chemical marker of the rhizome; no specific pharmacological activity of clinical relevance has been established for it.
Arundoin
Triterpene methyl ether (fernane-type)A fernane-type triterpene methyl ether reported consistently from the rhizome alongside cylindrin, fernenol and simiarenol. It contributes to the lipophilic fraction of the drug, which is largely absent from the water decoction in which the herb is actually used.
Fernenol
Triterpene alcohol (fernane-type)A triterpene alcohol of the rhizome, reported together with cylindrin, arundoin and simiarenol as the classical triterpene group of this drug.
Simiarenol
Triterpene alcoholA further pentacyclic triterpene alcohol of the rhizome. Twenty-six triterpenoids in total have been reported from the plant, including rare E:B-friedo-hopane types.
Imperanene
Phenolic lignan-type compoundReported as a platelet aggregation inhibitor isolated from the rhizome. This is the constituent most often invoked to rationalise the herb's traditional use in bleeding patterns, which is an awkward fit given that inhibiting platelet aggregation would be expected to worsen rather than stop bleeding.
Cylindrene
SesquiterpenoidA sesquiterpenoid of the rhizome with reported activity on vascular smooth muscle; the literature describes it inconsistently as a vasodilator and as having vasoconstriction activity, so the direction of its effect should not be relied upon clinically.
Cylindol A
Biphenyl ether lignanReported as a 5-lipoxygenase inhibitor from the rhizome, which is a plausible contributor to the anti-inflammatory activity attributed to the drug. The finding is from isolated-enzyme and cell work only.
Graminone B
LignanA lignan of the rhizome reported alongside cylindol A and B and imperanene in the phenolic fraction.
Imperphenoside A and imperlignanosides A-D
Phenolic and lignan glycosidesAmong ten previously undescribed phenolic constituents characterised from the rhizome of Imperata cylindrica var. major, the pharmacopoeial variety. Several of the isolated compounds inhibited nitric oxide production in a concentration-dependent manner at 3, 10 and 30 micromolar in lipopolysaccharide-stimulated cells.
Chlorogenic acid
Hydroxycinnamic acid esterOne of the water-extractable phenolic acids of the rhizome, reported with caffeic and ferulic acid. These are the constituents most likely to be present in a conventional decoction of the herb.
Potassium salts
Inorganic mineral constituentThe rhizome is described as having a high potassium content, and reviews attribute part of the traditional diuretic reputation of the drug to it. The one controlled human trial of the herb found no diuretic effect, so this rationale should be regarded as unconfirmed in people.
Polysaccharides
PolysaccharideHot-water-extractable polysaccharides of the rhizome have been profiled and reported to have immunomodulatory activity in cell-based assays. They are among the few constituents that would be substantially present in the decoction as actually prescribed.
⚠ Drug Interactions
Loop and thiazide diuretics (furosemide, hydrochlorothiazide)
Bai Mao Gen is classified as a heat-clearing, urination-promoting drug and is routinely assumed to add to pharmaceutical diuretics. The only controlled human test of that assumption is a placebo-controlled double-blind crossover study in healthy Vietnamese volunteers, in which Imperata cylindrica, along with Zea mays, Plantago major and Orthosiphon stamineus, produced no influence on 12-hour or 24-hour urine output and no influence on sodium excretion. Animal work suggests mechanisms involving renal blood flow and antidiuretic hormone release, but the human negative result is the higher-quality evidence and the authors themselves concluded that recommendations for these plant materials need critical review.
Clinical note: Do not counsel a patient to reduce a prescribed diuretic because they are taking this herb, and do not expect it to substitute for one. Monitor as you normally would; there is no evidence base for a dose adjustment in either direction.
Potassium-sparing diuretics, ACE inhibitors and angiotensin receptor blockers
Reviews of the drug describe a high potassium content in the rhizome and attribute part of its diuretic reputation to that mineral load. A decoction of the pharmacopoeial 9 to 30 g daily would deliver only a modest amount of potassium, and no case of hyperkalaemia attributable to this herb has been reported. The concern is arithmetic rather than observed.
Clinical note: No routine action. In a patient with impaired renal function on spironolactone or an ACE inhibitor whose potassium is already at the top of range, count the herb as one more dietary potassium source rather than as a distinct hazard.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 9–30 g | daily | — | adult | 中国药典 2020年版 一部 【白茅根】【用法与用量】9～30g。 — Chinese Pharmacopoeia 2020, Vol. I. |
Evidence Tier
Limited evidence · 2 studiesRecorded studies by study design, strongest design at the top. This is a study-design tier only, not a GRADE rating: it does not weigh risk of bias, consistency or precision.
Systematic review / meta-analysis
0
Randomized controlled trial
0
Other clinical trial
1
1 verified · 0 unverified
Observational / case report
0
In vitro / animal
1
1 verified · 0 unverified
Other / unclassified
0
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
Studies on the individual and combined diuretic effects of four Vietnamese traditional herbal remedies (Zea mays, Imperata cylindrica, Plantago major and Orthosiphon stamineus)
A placebo-controlled double-blind crossover study of four Vietnamese herbal diuretics, including Imperata cylindrica, tested under standardised conditions. No influence was recorded on 12-hour or 24-hour urine output, and none on sodium excretion, for any of the four drugs. The authors concluded that current recommendations for therapy with these plant materials need critical review. This remains the only controlled human test of the herb's best-known indication and it is negative.
Structural characterization of phenolic constituents from the rhizome of Imperata cylindrica var. major and their anti-inflammatory activity
Ten previously undescribed phenolic constituents, named imperphenoside A, imperphenols B and C, imperphenosides D to F and imperlignanosides A to D, were isolated from the rhizome of the pharmacopoeial variety Imperata cylindrica var. major together with thirty-seven known compounds. Eleven of the compounds inhibited nitric oxide production in a concentration-dependent way at 3, 10 and 30 micromolar in lipopolysaccharide-stimulated cells. The work identifies plausible anti-inflammatory constituents but is entirely cell-based.
⚠ Safety & Contraindications
Side Effects
- Essentially nontoxic; occasional dizziness, nausea and slightly increased bowel movements.
Source: Zhu YP. Chinese Materia Medica: Chemistry, Pharmacology and Applications. Harwood Academic, 1998, p. 410.
Historical Texts
Shen Nong Ben Cao Jing
Han dynastyZhou Hou Bei Ji Fang
Jin dynastyQian Jin Yi Fang
Tang dynastyBen Cao Gang Mu
Ming dynastyReferences
- Jung YK, Shin D. Imperata cylindrica: A Review of Phytochemistry, Pharmacology, and Industrial Applications . Molecules (2021) [DOI]
- Li J, Wang C, Zhan H, Wang X, Guan W, Zhao Y, Xu Z. Imperata cylindrica (L.) Raeusch.: a narrative review of phytochemistry, pharmacology, ethnopharmacology, botany, and comprehensive utilization . Frontiers in Pharmacology (2026) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
📝 Notes
Public notes from the community and your own private notes on Bai Mao Gen.
No notes yet.