Plant Profile

Bay-leaf willowherb

Epilobium parviflorum
Family: Onagraceae  ·  Parts used: Aerial parts (herb)  ·  Also known as: Small-flowered willowherb, Hoary willowherb

The complete database record: 3 documented constituents, 4 pharmacological actions, 9 traditional / indicated uses, with 16 cited sources.

Botanical Description

Slender, softly hairy perennial herb with narrow, lance-shaped leaves and small, four-petalled, pale pink to lilac flowers with a notched tip, borne singly in the upper leaf axils. After flowering, long, narrow seed pods split to release cottony-tufted seeds, typical of the willowherb genus.[13]

Height: 20-60 cm
Habit: Slender, softly hairy, erect perennial herb
Leaves: Narrow, lance-shaped, softly hairy
Flowers: Small, four-petalled, pale pink to lilac, notched, borne singly in upper leaf axils
Stem: Slender, softly hairy, erect
Root: Fibrous root with short rhizome
Fruit: Long, narrow seed pod releasing cottony-tufted seeds
Flowering Period: June-September

Habitat & Distribution

Grows in damp meadows, ditches, streamsides and waste ground on moist soils; native to Europe and temperate Asia.[13]

Harvesting

The flowering aerial parts are cut in summer while in flower, and dried in a warm, shaded, airy place.[13]

Parts: Aerial parts (herb)
Season: Summer flowering period

Key Constituents

Macrocyclic ellagitannins (notably oenothein B)[4, 5, 6, 7, 8, 13]

Characteristic Epilobium polyphenols underlying the anti-inflammatory and prostate activity; a genus review identifies oenothein B as the dominant constituent and likely driver of the antimicrobial, anti-inflammatory, anti-proliferative and antioxidant effects.

TanninsPhenolic compounds
Flavonoids (myricetin and quercetin glycosides)[11, 13]

Antioxidant constituents.

FlavonoidsGlycosidesQuercetin
Plant sterols (beta-sitosterol)[13]

Sterols associated with benign prostatic hyperplasia support.

Phytosterols

Pharmacological Actions

Anti-inflammatory[1, 3, 4, 6, 10, 13]

Anti-inflammatory (inhibits COX-1 and COX-2 prostaglandin synthesis)

Anticancer (preclinical)[3]
Antimicrobial[13]

Antibacterial, including against Escherichia coli (urinary support)

Antioxidant[1, 6, 9, 10, 11, 13]

Antioxidant (hydroxyl-radical scavenging)

Traditional & Indicated Uses

Arthritis / joint pain[13]Preliminary · 1/10

inferred from anti-inflammatory action

Evidence: 1
Label: Arthritis / joint pain

more plants for arthritis / joint pain →detailed sources →

Cancer (anticancer research)[3]Preliminary · 2/10

inferred from anticancer action

Evidence: 2
Label: Cancer (anticancer research)

more plants for cancer (anticancer research) →detailed sources →

Infection (general)[13]Preliminary · 1/10

inferred from antimicrobial action

Evidence: 1
Label: Infection (general)

more plants for infection (general) →detailed sources →

Inflammation (general)[13]Preliminary · 1/10

inferred from anti-inflammatory action

Evidence: 1
Label: Inflammation (general)

more plants for inflammation (general) →detailed sources →

Prostate support[4, 13, 16]Moderate · 5/10

Supports lower urinary tract symptoms of benign prostatic hyperplasia (prostate support) - a genus Epilobium review notes traditional BPH use attributed mainly to oenothein B, though clinical evidence is not yet conclusive

Evidence: 5
Label: Prostate support

more plants for prostate support →detailed sources →

Skin irritation[13]Preliminary · 1/10

inferred from anti-inflammatory action

Evidence: 1
Label: Skin irritation

more plants for skin irritation →detailed sources →

Urinary support[4, 13, 16]Moderate · 5/10

Antibacterial, including against Escherichia coli (urinary support); Supports lower urinary tract symptoms of benign prostatic hyperplasia (prostate support) - a genus Epilobium review notes traditional BPH use attributed mainly to oenothein B, though clinical evidence is not yet conclusive

Evidence: 5
Label: Urinary support

more plants for urinary support →detailed sources →

Urinary tract infection (UTI)[4, 13, 16]Moderate · 5/10

Supports lower urinary tract symptoms of benign prostatic hyperplasia (prostate support) - a genus Epilobium review notes traditional BPH use attributed mainly to oenothein B, though clinical evidence is not yet conclusive

Evidence: 5
Label: Urinary tract infection (UTI)

more plants for urinary tract infection (uti) →detailed sources →

Wounds[13]Preliminary · 1/10

inferred from antimicrobial action

Evidence: 1
Label: Wounds

more plants for wounds →detailed sources →

Traditional Use & History

Small-flowered willowherb, along with related Epilobium species, has a Central European folk tradition as a supportive remedy for lower urinary tract symptoms associated with benign prostatic hyperplasia (BPH) and prostatitis, and as an antimicrobial and anti-inflammatory herb for minor infections; the traditional prostate-support use is attributed mainly to its oenothein B content, though robust clinical evidence remains limited.[13]

Preparations

Infusion[13]

Dried flowering herb infused in hot water as a traditional urinary and prostate-support tea.

Dosage

Infusion[15]

The EU herbal monograph gives 1.5-2.0 g of the comminuted herb in 250 mL of boiling water as an infusion, twice daily, in adults and elderly; long-term use is possible. Lower urinary tract or prostate symptoms should always be medically assessed first, and the monograph directs that a doctor be consulted if fever, spasms, blood in the urine, painful urination or urinary retention occur. Educational reference only, not a prescription.

Safety, Cautions & Contraindications

Safety note[16]Info

Lower urinary tract / prostate symptoms must be medically assessed first to exclude prostate cancer; willowherb is a supportive measure, not a substitute for diagnosis and treatment.

Safety note[16]Info

Well tolerated over three months in clinical use; longer-term safety data are limited.

Harvest Readiness

[14]

Part: aerial-parts
Signals: Cut the flowering aerial parts (herb) in summer, while the plant is in flower.
Basis: traditional
Source Quote: It is in flower from July to August.
Species Confirmed: 1
Notes: PFAF (REF-3252); the medicinal part is the flowering aerial herb, gathered in summer while in flower (in flower July-August). PFAF gives the flowering stage rather than an explicit harvest sentence; flowering-herb collection is the standard stage for Epilobium. Single lineage -> provisional.

External Identifiers

References & Sources

  1. Vitalone, A. and Allkanjari, O (2018) 'Epilobium spp: Pharmacology and Phytochemistry', Phytotherapy Research, 32(7), pp. 1229-1240. doi:10.1002/ptr.6072 Traditional / reference
    https://doi.org/10.1002/ptr.6072
  2. Cicero, A.F.G., Allkanjari, O., Busetto, G.M., Cai, T. et al (2019) 'Nutraceutical treatment and prevention of benign prostatic hyperplasia and prostate cancer', Archivio Italiano di Urologia e Andrologia, 91(3), pp. 139-152. doi:10.4081/aiua.2019.3.139 Traditional / reference
    https://doi.org/10.4081/aiua.2019.3.139
  3. Vlase, A.M., Toiu, A., Gligor, O., Muntean, D. et al (2024) 'Investigation of Epilobium hirsutum L. Optimized Extract's Anti-Inflammatory and Antitumor Potential', Plants (Basel), 13(2), pp. 198. doi:10.3390/plants13020198 Preclinical
    https://doi.org/10.3390/plants13020198
  4. Granica, S., Piwowarski, J.P., Czerwinska, M.E. and Kiss, A.K (2014) 'Phytochemistry, pharmacology and traditional uses of different Epilobium species (Onagraceae): a review', Journal of Ethnopharmacology, pp. 316--346. doi:10.1016/j.jep.2014.08.036 Traditional / reference
    https://doi.org/10.1016/j.jep.2014.08.036
  5. Ramstead, A.G., Schepetkin, I.A., Quinn, M.T. and Jutila, M.A (2012) 'Oenothein B, a cyclic dimeric ellagitannin isolated from Epilobium angustifolium, enhances IFN-gamma production by lymphocytes', PLoS One, 7(11), pp. e50546. doi:10.1371/journal.pone.0050546 Preclinical
    https://doi.org/10.1371/journal.pone.0050546
  6. Kiss, A.K., Bazylko, A., Filipek, A., Granica, S., Jaszewska, E., Kiarszys, U., Kosmider, A. and Piwowarski, J (2011) 'Oenothein B's contribution to the anti-inflammatory and antioxidant activity of Epilobium sp', Phytomedicine, 18(7), pp. 557-560. doi:10.1016/j.phymed.2010.10.016 Preclinical
    https://doi.org/10.1016/j.phymed.2010.10.016
  7. Schepetkin, I.A., Kirpotina, L.N., Jakiw, L., Khlebnikov, A.I., Blaskovich, C.L., Jutila, M.A. and Quinn, M.T (2009) 'Immunomodulatory activity of oenothein B isolated from Epilobium angustifolium', Journal of Immunology, 183(10), pp. 6754-6766. doi:10.4049/jimmunol.0901827 Preclinical
    https://doi.org/10.4049/jimmunol.0901827
  8. Ducrey, B., Marston, A., Gohring, S., Hartmann, R.W. and Hostettmann, K (1997) 'Inhibition of 5-alpha-reductase and aromatase by the ellagitannins oenothein A and oenothein B from Epilobium species', Planta Medica, 63(2), pp. 111-114. doi:10.1055/s-2006-957624 Preclinical
    https://doi.org/10.1055/s-2006-957624
  9. Schepetkin, I.A., Ramstead, A.G., Kirpotina, L.N., Voyich, J.M., Jutila, M.A. and Quinn, M.T (2016) 'Therapeutic potential of polyphenols from Epilobium angustifolium (fireweed)', Phytotherapy Research, 30(8), pp. 1287-1297. doi:10.1002/ptr.5648 Meta-analysis / review
    https://doi.org/10.1002/ptr.5648
  10. Merighi, S., Travagli, A., Tedeschi, P., Marchetti, N. and Gessi, S (2021) 'Antioxidant and anti-inflammatory effects of Epilobium parviflorum, Melilotus officinalis and Cardiospermum halicacabum plant extracts in macrophage and microglial cells', Cells, 10(10), pp. 2691. doi:10.3390/cells10102691 Preclinical
    https://doi.org/10.3390/cells10102691
  11. Hevesi Toth, B., Blazics, B. and Kery, A (2009) 'Polyphenol composition and antioxidant capacity of Epilobium species', Journal of Pharmaceutical and Biomedical Analysis, 49(1), pp. 26-31. doi:10.1016/j.jpba.2008.09.047 Preclinical
    https://doi.org/10.1016/j.jpba.2008.09.047
  12. Vitalone, A., McColl, J., Thome, D., Costa, L.G. and Tita, B (2003) 'Characterization of the effect of Epilobium extracts on human cell proliferation', Pharmacology, 69(2), pp. 79-87. doi:10.1159/000072360 Preclinical
    https://doi.org/10.1159/000072360
  13. Steenkamp, V., Gouws, M.C., Gulumian, M., Elgorashi, E.E. and van Staden, J (2005) 'Studies on antibacterial, anti-inflammatory and antioxidant activity of herbal remedies used in the treatment of benign prostatic hyperplasia and prostatitis', Journal of Ethnopharmacology, pp. 2005. doi:10.1016/j.jep.2005.07.007 Traditional / reference
    https://doi.org/10.1016/j.jep.2005.07.007
  14. Plants For A Future 'Epilobium parviflorum (Small-flowered Willowherb, Hoary Willowherb)'. Available at: https://pfaf.org/user/Plant.aspx?LatinName=Epilobium+parviflorum Traditional / reference
    https://pfaf.org/user/Plant.aspx?LatinName=Epilobium+parviflorum
  15. European Medicines Agency (HMPC) (2015) 'European Union herbal monograph on Epilobium angustifolium L. and/or Epilobium parviflorum Schreb., herba'. Available at: https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-epilobium-angustifolium-l-andor-epilobium-parviflorum-schreb-herba_en.pdf Traditional / reference
    https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-epilobium-angustifolium-l-andor-epilobium-parviflorum-schreb-herba_en.pdf
  16. Coulson, S., Rao, A., Beck, S.L., Steels, E., Gramotnev, H. and Vitetta, L (2013) 'A phase II randomised double-blind placebo-controlled clinical trial investigating the efficacy and safety of ProstateEZE Max: a herbal medicine preparation (containing Epilobium parviflorum) for the management of symptoms of benign prostatic hypertrophy', Complementary Therapies in Medicine. doi:10.1016/j.ctim.2013.01.007 Randomized trial
    https://doi.org/10.1016/j.ctim.2013.01.007

This fact sheet is generated automatically from the Omnia Sana plant database and reflects its latest synced data. It is provided for educational purposes only and is not medical advice. How this site is built.

Selected studies & references

Educational use only. This profile summarises traditional and scientific sources for reference. It is not medical advice and not a substitute for a qualified practitioner. Some plants carry safety cautions and drug interactions - always check before use.
This profile is assembled automatically from the Omnia Sana plant database, which we curate by hand. How this site is built.
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