Fu Ping
StarSpirodela polyrhiza
Synonyms: Lemna polyrhiza var. concolor, Spirodela atropurpurea, Lemna umbonata, Lemna orbicularis, Lenticula polyrrhiza, Lemna major, Lemna polyrhiza, Lemna maxima, Lemna bannatica, Lemna transsilvanica, Spirodela polyrhiza var. masonii, Telmatophace orbicularis, Telmatophace polyrhiza, Lemna thermalis, Lemna orbiculata, Spirodela maxima
Traditionally used for
- Colds & fever
- Urinary & fluids
- Skin
☯ TCM Properties
Induces sweating and releases the exterior; Vents rashes and relieves itching; Promotes urination and reduces swelling
Traditional Chinese Uses
Fu Ping (duckweed, Spirodela polyrrhiza) is a cool, acrid herb used to expel Wind-Heat from the Exterior and promote urination. It is helpful for early-stage Wind-Heat invasion with fever and absent sweating, and for facilitating the expression of measles and other rashes erupting slowly. Its light, floating nature also supports urinary function, making it applicable for edema from Wind-Water patterns.
Western Herbalism Properties
Relationships
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Botanical Description
Spirodela polyrhiza is a free-floating aquatic plant in the duckweed family (Araceae subfamily Lemnoideae). It consists of flat, oval, thallus-like fronds 3-10 mm long and 2-8 mm wide, purple or reddish-purple on the lower surface and dark green on the upper. Each frond has 5-16 roots hanging beneath and produces 1-2 daughter fronds via budding. Flowers and fruits are tiny and rarely produced. It is the largest of the common duckweed species. Whole dried thalli are used medicinally.
Still or slow-moving freshwater bodies including ponds, lakes, rice paddies, ditches, and marshes; found throughout tropical, subtropical, and warm temperate regions worldwide.
Spirodela polyrhiza is one of the most widespread aquatic plants on Earth, found on every continent except Antarctica. It is extremely common in suitable freshwater habitats. No conservation concerns.
Active Constituents
Vitexin (apigenin 8-C-glucoside)
Flavone C-glycosideConcentration: One of the four principal flavonoids of the drug; a major peak in 30 percent ethanolic extracts
Vitexin inhibits the calcium release-activated calcium (CRAC) current carried by ORAI1. At 100 micromolar it reduced CRAC current in Jurkat T cells and RBL-2H3 mast cells and cut both T-cell proliferation and IgE-triggered mast cell degranulation without cytotoxicity. That is a coherent molecular account of the classical indication for wind-rash and itching, though it is cell-line work at a concentration far above anything a decoction achieves in plasma.
Orientin (luteolin 8-C-glucoside)
Flavone C-glycosideConcentration: One of the four principal flavonoids; quantified by HPLC in ethanolic extracts
The luteolin counterpart of vitexin and, with it, the most active of the drug's flavonoids in suppressing adipogenesis in 3T3-L1 cells by lowering C/EBP-alpha and PPAR-gamma. It is also a marker used to standardise Spirodela-containing dermatological preparations.
Luteolin and luteolin 7-O-glucoside (cynaroside)
Flavone and flavone O-glycosideConcentration: Among the four major flavonoids of the drug
Luteolin inhibits the calcium-activated chloride channel TMEM16A/ANO1, which is upregulated by interleukin-4 in airway and nasal gland serous cells and drives watery secretion. In patch clamp and Ussing chamber work a 30 percent ethanolic Spirodela extract and luteolin both suppressed the calcium-activated chloride current without touching CFTR. Luteolin also shows strong docking affinity for TNF and IL-6.
Apigenin and apigenin 7-O-glucoside (apigetrin, cosmosin)
Flavone and flavone O-glycosideConcentration: Among the four major flavonoids of the drug
Contributes to the anti-inflammatory profile identified in mouse contact dermatitis work, where apigenin and luteolin were the constituents with the strongest predicted binding to TNF and IL-6. Apigenin is ubiquitous in edible plants and does not on its own authenticate the drug.
Chrysoeriol
Methoxylated flavoneConcentration: Minor flavonoid constituent
One of the isolated flavones of Spirodela polyrhiza alongside apigenin, luteolin, vitexin, cosmosin and orientin. It contributes to the total flavonoid load but has no drug-specific pharmacology established for this species.
Anthocyanins of the purple frond underside
Anthocyanin (flavonoid)Concentration: Variable, light- and stress-induced; concentrated in the abaxial frond surface
Pharmacologically minor but diagnostically central. Li Shizhen distinguished two duckweeds - one green on both faces (qing ping) and one purple-red beneath (zi ping) - and it is zi ping, Spirodela polyrhiza, that the 2020 Chinese Pharmacopoeia recognises as the sole official Fu Ping. The purple underside is how a practitioner tells them apart in the dispensary.
Potassium salts (potassium acetate and potassium chloride)
Inorganic saltConcentration: Notable mineral fraction of the dried herb, reported consistently in materia medica sources
The classical claim that Fu Ping drains water faster than Tong Cao has a plausible osmotic basis in its potassium salt load. The same fact makes it a potassium source of unquantified size, which matters when it is combined with drugs that retain potassium.
Arsenic accumulated from the growing water
Metalloid contaminant acquired by hyperaccumulationConcentration: Variable and site-dependent, but Spirodelae herba was classified as a HIGH-degree arsenic contamination risk in an ICP-MS survey of 10,245 samples across 279 Chinese herbal medicines (Yang et al., 2021)
This is the defining safety fact about Fu Ping and it follows directly from its biology. Spirodela polyrhiza is deliberately used to strip arsenic from contaminated water: Rahman et al. (2007) showed it takes up arsenate through the phosphate transport pathway and by adsorption onto iron oxides, with uptake rising sharply when ambient phosphate is low. A plant selected for its ability to concentrate arsenic out of water, then harvested from open water of unknown quality, is an arsenic exposure route by design rather than by accident.
Cadmium and other heavy metals accumulated from the growing water
Heavy-metal contaminants acquired by hyperaccumulationConcentration: Variable and site-dependent; concentration- and duration-dependent in culture, with 52 to 61 percent of accumulated cadmium bound in the cell wall and 37 to 46 percent soluble
The same hyperaccumulator physiology applies to cadmium, copper, chromium and silver, and duckweed root growth is sensitive enough to serve as a bioassay for copper and chromium contamination. Chen et al. (2020) found large variation in cadmium accumulation between 30 wild accessions from southern China, so provenance changes the metal load even within the species.
⚠ Drug Interactions
Arsenic trioxide, realgar-containing Chinese patent medicines and other sources of inorganic arsenic
Yang et al. (2021) determined lead, arsenic, cadmium and mercury by validated ICP-MS in 10,245 samples of 279 Chinese herbal medicines and, by cluster analysis of exceedance rates, placed Spirodelae herba in the small group of drugs at high-degree risk of arsenic contamination, alongside kelp thallus and natural indigo. The mechanism is not contamination in the ordinary sense: the plant is a documented arsenic phytofiltrator that takes arsenate up through the phosphate pathway, so it concentrates whatever arsenic its water contains. Stacking it with a medicine that deliberately contains arsenic adds a known dose to an unknown one.
Clinical note: Do not combine with realgar-containing formulas or with arsenic trioxide therapy. Buy only from suppliers who provide batch arsenic figures, and refuse material of unstated provenance - wild-gathered Fu Ping and Fu Ping harvested from a wastewater or remediation pond are visually identical. Avoid prolonged courses, and avoid it altogether in patients already carrying an arsenic burden.
Potassium-sparing diuretics (spironolactone, amiloride), ACE inhibitors, angiotensin receptor blockers and potassium supplements
The dried herb carries a substantial potassium salt fraction, reported as potassium acetate and potassium chloride, which is part of the traditional explanation for its water-draining action. No study has measured the potassium content of a therapeutic dose or its effect on serum potassium, so the size of the contribution is unknown.
Clinical note: Check serum potassium in patients on potassium-retaining drugs or with chronic kidney disease if Fu Ping is used for more than a short course, rather than assuming a herb contributes no potassium.
Loop and thiazide diuretics
Fu Ping is prescribed to promote urination and reduce oedema, and the classical Ben Jing Feng Yuan states that its diaphoretic action exceeds that of Ma Huang and its water-draining is quicker than Tong Cao. Combining a strongly diaphoretic and diuretic herb with a pharmaceutical diuretic risks additive volume depletion, particularly in older patients. This is a pharmacodynamic prediction from the drug's stated action; no interaction study exists.
Clinical note: Watch for postural symptoms, and check urea, creatinine and electrolytes if the combination continues beyond a short course. The classical caution against Fu Ping in patients who already sweat easily or are deficient in qi applies with more force here.
Lithium
Lithium is handled by the kidney like sodium, and agents that alter sodium and water handling can change lithium clearance. Fu Ping is used specifically as a diuretic. There is no pharmacokinetic study of this herb with lithium, and the mechanism is a class-level inference.
Clinical note: Check lithium levels a week after starting or stopping Fu Ping in a patient on lithium, and warn the patient about signs of lithium toxicity.
Lemna minor (qing ping) substituted for Spirodela polyrhiza (zi ping)
The Ben Cao Gang Mu already recorded two duckweeds in use, one green on both faces and one purple-red beneath, and both have been used as Fu Ping historically. The 2020 Chinese Pharmacopoeia recognises only zi ping, Spirodela polyrhiza, as the official drug. Lemna minor is a smaller, single-rooted plant with a related but not identical flavonoid profile, and it shares the same hyperaccumulator behaviour, so a substituted batch carries the same heavy-metal question without the Pharmacopoeia's identity.
Clinical note: Check for the purple abaxial surface and the tuft of several roots per frond that distinguish Spirodela from the single-rooted Lemna. Where the research literature is invoked, note that most of the pharmacology cited here used S. polyrhiza specifically.
Antihistamines, mast cell stabilisers and calcineurin-pathway immunosuppressants
Spirodela extract and vitexin suppress ORAI1-mediated CRAC current, mast cell degranulation and T-cell proliferation in vitro, and luteolin blocks the IL-4-induced ANO1 chloride current that drives rhinorrhoea. Store-operated calcium entry through ORAI1 is upstream of calcineurin and NFAT, the target of ciclosporin and tacrolimus, so an additive immunosuppressive effect is conceivable. The in vitro concentrations (3 mg/mL extract, 100 micromolar vitexin) are far above plausible plasma levels, so this is a mechanistic flag, not a documented interaction.
Clinical note: No specific precaution for antihistamines. In a patient on a calcineurin inhibitor, record the herb and monitor as usual rather than assuming it is inert.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 3–9 g | daily | — | adult | 中国药典 2020年版 一部 【浮萍】【用法与用量】3～9g。外用适量，煎汤浸洗。 — Chinese Pharmacopoeia 2020, Vol. I. Contraindicated in exterior deficiency with spontaneous sweating. |
Evidence Tier
Moderate evidence · 8 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
0
Observational / case report
0
In vitro / animal
8
3 verified · 5 unverified
Show 8 studies
- Investigation of toxic heavy metals content and estimation of potential health risks in Chinese herbal medicine
- Arsenic accumulation in duckweed (Spirodela polyrhiza L.): A good option for phytoremediation
- Intraspecific variations in cadmium tolerance and phytoaccumulation in giant duckweed (Spirodela polyrhiza)
- Spirodela polyrhiza and its Chemical Constituent Vitexin Exert Anti-Allergic Effect via ORAI1 Channel Inhibition
- Luteolin reduces fluid hypersecretion by inhibiting TMEM16A in interleukin-4 treated Calu-3 airway epithelial cells
- Anti-Inflammatory Effects of Spirodela polyrhiza (L.) SCHLEID. Extract on Contact Dermatitis in Mice—Its Active Compounds and Molecular Targets
- A combination of Olea europaea leaf extract and Spirodela polyrhiza extract alleviates atopic dermatitis by modulating immune balance and skin barrier function in a 1-chloro-2,4-dinitrobenzene-induced murine model
- Vitexin, orientin and other flavonoids from Spirodela polyrhiza inhibit adipogenesis in 3T3-L1 cells
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
Investigation of toxic heavy metals content and estimation of potential health risks in Chinese herbal medicine
Analytical survey, not a clinical study: lead, arsenic, cadmium and mercury were determined by validated ICP-MS in 10,245 samples of 279 Chinese herbal medicines, exceedance rates calculated against several pharmacopoeial limits, and drugs clustered by degree of contamination risk. Spirodelae herba - Fu Ping - was one of only three drugs classified as high-degree risk for arsenic, with kelp thallus and natural indigo. This is the direct evidence that the plant's hyperaccumulator physiology reaches the dispensary. The survey does not report per-batch figures for Fu Ping or link them to any patient outcome, so it establishes the exposure and not the harm.
Arsenic accumulation in duckweed (Spirodela polyrhiza L.): A good option for phytoremediation
Hydroponic study establishing why Fu Ping is an arsenic risk. Plants grown for 6 days in 4.0 micromolar arsenate with 0.02 micromolar phosphate took up 0.353 micromol of arsenic per gram, roughly 46 times the uptake from dimethylarsinic acid at the same concentration. Arsenate uptake was negatively correlated with phosphate uptake, because arsenate and phosphate share a transport route, and positively correlated with iron uptake through adsorption onto iron oxides. The authors conclude the species is a good arsenic phytofiltrator. Read as a safety document rather than an environmental one, it says that duckweed grown in phosphate-poor arsenic-bearing water will concentrate arsenic efficiently.
Intraspecific variations in cadmium tolerance and phytoaccumulation in giant duckweed (Spirodela polyrhiza)
Thirty wild accessions of Spirodela polyrhiza from different provenances in southern China were exposed to 1 micromolar cadmium. Growth rate, frond number and area and photosynthetic pigments fell while hydrogen peroxide, lipid peroxidation and antioxidant enzyme activity rose in most accessions, with marked accumulation of cadmium and substantial variation between accessions. Relevant to the drug because it shows the metal load is not a fixed species property: two authentic Fu Ping batches from different waters can differ substantially in what they carry.
Spirodela polyrhiza and its Chemical Constituent Vitexin Exert Anti-Allergic Effect via ORAI1 Channel Inhibition
A 30 percent ethanolic Spirodela polyrhiza extract at 3 mg/mL and its constituent vitexin at 100 micromolar both reduced the calcium release-activated calcium current in Jurkat T lymphocytes and RBL-2H3 mast cells. Vitexin also inhibited human primary T-cell proliferation after CD3/CD28 co-stimulation and IgE-antigen-triggered mast cell degranulation, concentration-dependently and without cytotoxicity. The most mechanistically satisfying account of the herb's classical use for wind-rash and itching, but it is cell-line electrophysiology at concentrations well above any achievable plasma level.
Luteolin reduces fluid hypersecretion by inhibiting TMEM16A in interleukin-4 treated Calu-3 airway epithelial cells
Patch clamp and Ussing chamber study of a 30 percent ethanolic Spirodela polyrhiza extract and its five major flavonoids. Luteolin significantly inhibited human ANO1/TMEM16A current in transfected HEK293T cells, and both the extract and luteolin selectively suppressed the calcium-activated chloride current, but not CFTR current, in Calu-3 airway epithelial cells; luteolin also blocked ATP-induced electrolyte transport in IL-4-sensitised cells. Offers a channel-level mechanism for the herb's use in rhinorrhoea and watery discharge. Entirely in vitro.
Anti-Inflammatory Effects of Spirodela polyrhiza (L.) SCHLEID. Extract on Contact Dermatitis in Mice—Its Active Compounds and Molecular Targets
Spirodela polyrhiza extract reduced contact dermatitis in mice, with network and docking analysis identifying luteolin and apigenin as the constituents with strongest predicted binding to TNF and IL-6. Uses the correct species and an inflammatory skin endpoint that matches the classical indication for rashes and itching. It is a mouse model with computational target attribution, not a human trial, and no controlled human study of Fu Ping for any indication has been published.
A combination of Olea europaea leaf extract and Spirodela polyrhiza extract alleviates atopic dermatitis by modulating immune balance and skin barrier function in a 1-chloro-2,4-dinitrobenzene-induced murine model
Oral olive leaf extract plus Spirodela polyrhiza extract for 5 weeks in DNCB-induced atopic dermatitis in NC/Nga mice reduced dermatitis scores, epidermal thickness and inflammatory infiltrate, lowered serum IgE and histamine and Th2 cytokines IL-4, IL-5 and IL-13 while raising IFN-gamma, and restored filaggrin, sirtuin 1 and claudin 1. Note the design limitation: the benefit is reported for the combination, so nothing here is attributable to Spirodela alone.
Vitexin, orientin and other flavonoids from Spirodela polyrhiza inhibit adipogenesis in 3T3-L1 cells
The butanol-soluble fraction of Spirodela polyrhiza inhibited adipogenesis in 3T3-L1 preadipocytes, with vitexin and orientin the most active constituents in reducing C/EBP-alpha and PPAR-gamma protein expression. Cited here to characterise the flavonoid fraction, not to support any weight-related use: this is a preadipocyte cell line and there is no human evidence.
⚠ Safety & Contraindications
Contraindications
It is not suitable for patients with exterior deficiency accompanied by profuse sweating.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, pp. 26–31.
Historical Texts
Shen Nong Ben Cao Jing (Divine Husbandman's Classic of Materia Medica)
Han dynasty, c. 200 CEXin Xiu Ben Cao (Newly Revised Materia Medica, the Tang Materia Medica)
Tang dynasty, 659 CEBen Cao Gang Mu (Compendium of Materia Medica), Li Shizhen
Ming dynasty, 1596Ben Jing Feng Yuan (Encountering the Sources of the Classic of Materia Medica), Zhang Lu
Qing dynasty, 1695References
- Toporowska M, Zebracki K, Mazur A, Mazur-Marzec H, Sulcius S, Alzbutas G, Lukashevich V, Dziga D, Mieczan T. Biodegradation of microcystins by microbiota of duckweed Spirodela polyrhiza . Chemosphere (2024) [DOI]
- Rzodkiewicz LD, Turcotte MM. Two duckweed species exhibit variable tolerance to microcystin-LR exposure across genotypic lineages . Harmful Algae (2024) [DOI]
- Choi GY, Kim KJ, Park HS, Hwang ES, Cho JM, Kim HB, Kim DO, Park JH. Phenolic changes in a combined herbal extract of Lithospermum erythrorhizon, Houttuynia cordata, and Spirodela polyrhiza and alleviation of DNCB-induced atopic dermatitis in BALB/c mice . Food Science and Biotechnology (2024) [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.
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