Persicaria odorata
Vietnamese coriander
Generally recognised as safeOther names: Vietnamese mint, Laksa leaf, Polygonum odoratum
A Vietnamese knotweed-family herb with a sharp coriander-citrus aroma.
A creeping perennial with narrow leaves marked by subtle dark blotches; the fresh leaves have a sharp coriander-citrus flavor and accompany phở, spring rolls, and salads in Vietnamese cooking.
- Family
- Polygonaceae
- Plant type
- Perennial herb
What the safety levels mean (expand legend)
- Generally recognised as safe. Often a common herb with reasonable harvest and use; still read the specific warnings on the card.
- Information. Primarily informational — details in the text and warnings below matter most.
- Caution. Needs extra care (dose, duration, sensitive groups, interactions).
- Risky. Significant risks — verify sources, contraindications and professional guidance.
- Not for home experimentation. Not suitable to experiment with at home without knowledge and certainty.
- High risk for internal use. Particular risk with internal use (e.g. alkaloids); avoid prolonged or irresponsible dosing.
- Not specified. Level not filled in yet — rely on individual warnings and links below.
Photograph on Wikimedia Commons (CC BY-SA 4.0).
Plant habit
Quick overview
A practical summary; details are in the sections below.
- Safety grade
- Generally recognised as safe details
- Scientific sources on the card
- Yes — sources are listed with claims Science section
- When and what to harvest
- Leaf — January–December
- Processing methods
Culinary use, Poultice / compress
All methods and recipes on the card- Topics and symptoms
Bloating & gas, Digestion
Topics section, Symptoms overview
Identification and mix-ups
Sprawling short-lived perennial herb in Polygonaceae, about 15–30 cm tall, spreading to 60 cm. Leaves lance-shaped, narrow, pointed, with a distinctive dark brown-maroon chevron (V-shaped) marking on the upper surface. At each node a membranous fringed sheath (ocrea) bears long silky hairs at the apex. Flowers small, creamy-white to pale pink (rarely flowers in the tropics). Strong coriander scent when crushed.
Possible mix-ups and risks
Confusion with other Persicaria species (knotweeds), which differ in their ocrea structure and above all in the absence of the dark maroon chevron and the coriander scent. No toxic lookalike is documented — the genus is generally non-toxic, so confusion is a matter of flavour/quality, not poisoning.
Similar herbs
No related herbs are linked yet.
Topics and symptoms
More topics are in the symptoms and topics overview.
- Bloating & gasCulinary· Traditional / cultural framingTraditional· Traditional / cultural framing
- DigestionTraditional· Traditional / cultural framing
Sources
Geographic occurrence
Viet Nam
Common (expected wild occurrence in the region)
Harvest
- LeafJanuary–December
year-round
Region: Viet NamNotes: Young fresh shoots from a constantly moist substrate.
Storage
- Refrigeration(Leaf)
Fresh stems with leaves keep a week in the fridge in a glass of water or in damp paper; they root easily and can be grown in a pot. Drying kills the scent — it is not dried; chopped leaves can be frozen in oil.
- Moisture:
- In a sealed bag the leaves blacken.
Processing methods on this herb card
Cooking, baking, seasoning as food — general category without therapeutic claims.
Full method description (from the catalogue)
Culinary use covers herbs as ingredients in dishes, drinks, or spice mixes. This overview does not evaluate medicinal effects — only reminds you about species intent, allergies, and heat treatment where needed (e.g. some fruits or plant parts).
Combining with alcohol, sugar, or long cooking changes outcomes; verify culinary sources.
Traditional context for this method: yes·Scientific context for this method: no
Liquid or paste on the skin, often through a thin cloth.
Full method description (from the catalogue)
A compress applies moist warm or cool material to the skin directly or through fabric. Duration and temperature are key — too hot can burn; too long can macerate the skin.
Use clean textiles and watch skin reaction during the first minutes.
Traditional context for this method: yes·Scientific context for this method: no
Traditional / spiritual use
Kept separate from science — entries are cultural or symbolic, not medical advice.
Rau ram with embryo eggs, and the tale of cooled desire
General
Folk beliefFolk useHerbal loreSuperstitionIn Vietnam rau ram is served with trung vit lon, duck eggs with a developed embryo, because folk medicine says it balances their 'hot' nature. From this comes the saying that rau ram dampens desire — Buddhist monks are said to eat it for that reason and young couples are advised against it. In Malaysia daun kesum is the soul of laksa soup. A record of folk belief; no one has measured an effect on libido.
- Form:
- an herb that "cools desire" — a Vietnamese proverb
- Claim strength:
- Tradition
- Source note:
- Vietnamese folk tradition (trung vit lon, the rau ram saying); Dung NX et al. (1995), J Essent Oil Res 7:339–340 (composition).
Scientific notes
Each claim lists a study type and a source (URL or DOI) where available. Dose notes from the literature are informational only.
How to read evidence strength and study type labels
Labels summarise how the catalogue entry is tagged — they are not a medical verdict on efficacy. For every row, read the summary, limitations and source link.
Evidence strength
- Evidence level not specified
- The author did not grade the record; judge from the summary, limitations and source link.
- Narrative / orientational literature
- Descriptive or expert literature without controlled group comparison — context rather than proof of effect.
- Weak evidence
- Study or conclusion with major methodological limits; treat only as a pointer for further reading.
- Preliminary findings
- First or smaller studies — interesting direction, not the final word on efficacy or safety.
- Moderate strength of evidence
- Moderate strength by study design; sample and context limits still apply.
- Stronger evidence
- Stronger design or consistency of results within the study's stated limits.
- Review article
- A review summarises multiple sources; quality depends on review method and field.
Study type
- Narrative / expert text
- Expert text or overview without a classical study design.
- In vitro study
- Cell culture or test-tube experiment — does not show an effect in the body.
- Animal study
- Animal model — transfer to humans is not automatic.
- Observational study
- Observing groups without random treatment assignment; confounding is possible.
- Clinical trial
- Human clinical trial; sample size and control group matter.
- Randomised controlled trial
- Randomised controlled trials are among the stronger designs when well conducted.
- Review study
- A review aggregates multiple papers — quality depends on selection rules.
- Systematic review
- Systematic review with explicit search and selection methodology.
- Meta-analysis
- Statistical pooling of studies; outcome depends on input data and heterogeneity.
- Regulatory assessment / monograph (EMA, WHO…)
- Regulatory body summary for a herbal product — different context from a single RCT; often about products, not home tea.
- Expert monograph (herbal preparations)
- Structured literature summary for a plant or drug — quality depends on author and edition year.
Analysis of the essential oil of Vietnamese rau ram showed a predominance of aliphatic aldehydes — decanal and dodecanal — with smaller shares of decanol and sesquiterpenes; a chemical description of the aroma, not a study of effect.
Narrative / orientational literatureNarrative / expert textYear: 1995Limitations: Chemical analysis of a single population; no pharmacological or clinical data.
Dũng NX, Hac LV, Leclercq PA — Journal of Essential Oil Research
Volatile Constituents of the Aerial Parts of Vietnamese Polygonum odoratum L.
Images
The main photo is in the card header. More images will appear here when available.
Safety
What the warning types mean
The type on each warning helps group themes — it does not replace the separate severity badge.
- Internal use
- Risks from swallowing, extracts, duration of use or concentration for internal use.
- Interactions / medicines
- Possible effect on medicines or concurrent treatment — check sources and a professional.
- Raw plant parts
- Raw, unripe or poorly prepared plant parts can be dangerous.
- Toxins and regulation
- Toxic constituents or regulated compounds (e.g. in distillates).
- Contact with the plant
- Skin or mucosa irritation from contact with fresh plant or sap.
- Allergy
- Allergic reactions, often linked to family sensitisation.
- Harvesting and contamination
- Contamination, species mix-ups or harvesting from unsuitable places.
No structured safety records yet.