© Jan Eckstein · CC BY-SA 3.0 · Commons
Mercurialis annua
Caution🐾Einjähriges Bingelkraut · (Mercurialis annua)
Spurge family (Euphorbiaceae)
Description
Crush or let annual mercury wilt and its odd, fish-like smell becomes obvious — a result of the amines methylamine and trimethylamine it contains. This latex-free weed grows as an arable companion plant and is considered an indicator of nitrogen-rich, disturbed soil; the flowering herb is gathered between June and August. It also contains the saponin glycoside mercurialin along with tannins and flavonoids. Historically it appeared in herbals and was used as a dye plant, but it has no modern medicinal use. Taken internally the plant is mildly toxic and can cause nausea, vomiting, abdominal pain and gastrointestinal irritation, with circulatory disturbance possible at larger amounts. It can be confused with the more toxic dog's mercury, with brooklime, and with young Chenopodium plants, so caution is needed when foraging.
🌿 Risk of confusion — read before wild-harvesting!
Risk of confusion with the more toxic Mercurialis perennis (perennial root, unbranched stem), with brooklime (Veronica beccabunga) and with Chenopodium species in the young stage — caution when foraging.
CONTRAINDICATED during pregnancy
Internal use during pregnancy is STRICTLY CONTRAINDICATED. Historical sources attribute emmenagogue and abortifacient action to bingelkraut (Hildegard, medieval gynaecology) — saponins and methylamines can affect smooth muscle including the uterus. External contact with plant sap (e.g. during dye experiments) should also be avoided during pregnancy, as data on percutaneous absorption are lacking.
CONTRAINDICATED during breastfeeding
Internal use during lactation is CONTRAINDICATED — methylamines and saponins may pass into breast milk and cause nausea, vomiting and gastrointestinal irritation in the infant. Historical 'breast poultices' for milk stasis are obsolete and explicitly not recommended.
CONTRAINDICATED for children
STRICTLY AVOID in children — children are more sensitive to saponins and methylamines than adults. Accidental ingestion of a few leaves while playing usually causes only nausea and vomiting, but larger amounts can lead to gastroenteritis and circulatory problems. If ingestion is suspected: rinse the mouth, give plenty of water, DO NOT induce vomiting, and contact a poison control centre.
Critical drug interactions with:
Herzglykoside (Digitoxin, Digoxin) · Diuretika und Abführmittel · Antikoagulantien und Thrombozytenaggregationshemmer
Historic dye tradition (vivid blue plant pigment): for centuries Mercurialis annua was one of Europe's most important dye plants for blue-violet and purple shades — especially in France (Languedoc, Provence) and on the Iberian peninsula. Enzymatic oxidation of the colourless precursor hermidin yields chrysohermidin and related quinoid pigments. These were traded mainly as 'tournesol en drapeaux' or 'tournesol des teinturiers' (dyers' tournesole): linen rags impregnated with Mercurialis sap and ammonia (from urine), used to colour cheese rinds (Edam, Gouda), sugar loaves and inexpensive textiles. Owing to its pronounced light sensitivity the dye is suitable only for temporary markings and ephemeral colourings.
Medieval folk medicine (today OBSOLETE, historical documentation only): Hildegard of Bingen mentions bingelkraut ('Bingilcrut') in her 'Physica' (12th century) as a mild laxative for constipation and 'mucus in the belly'. Dioscorides (1st c.) and Galen (2nd c.) already described Mercurialis as digestion-stimulating, vermifuge and 'evacuating bad humours'. Infusions of the fresh or dried herb were considered a gentle laxative until the 18th century. Owing to the now-known toxicity of saponins and methylamines (nausea, gastroenteritis) and the absence of modern efficacy data, this use is TODAY OBSOLETE and is documented purely for the history of medicine — not for self-medication.
Famine food (RISKY, only historically documented): in some Mediterranean regions (Spain, southern Italy, Greece) young shoots of Mercurialis annua were boiled extensively in lean times — typically boiled several times in fresh water, discarding the cooking water each time to leach out saponins and methylamines — and eaten with other wild greens. The practice is well attested for crisis and war years of the 19th and early 20th century. Owing to unreliable detoxification and the risk of confusion with the more toxic perennial dog's mercury (Mercurialis perennis), M. annua is NOT a recommended wild vegetable. Modern culinary use is explicitly not advised.
Historical external use (OBSOLETE, documentation only): in medieval and early modern folk medicine, crushed fresh bingelkraut leaves were applied as poultices to ulcers, poorly healing wounds and skin rashes ('itch', eczema). Lonicerus (herbal of 1557) and Matthioli additionally mention its use as a chest compress for milk stasis and as an 'emollient plaster'. No pharmacological basis for these applications is documented; the saponin-containing plant can in fact cause redness on sensitive skin. Today: documentary interest only — no application recommended.
Ecology and garden indicator: annual mercury is a typical nitrogen- and tilled-crop weed of loose, nutrient-rich soils (gardens, fields, vineyards, waste places). It indicates fresh, basic-to-neutral, well-fertilised soil with mull or mull-moder humus (Ellenberg indicator values N=8, R=7). For home gardeners it is a useful indicator of well-supplied beds; at the same time it competes vigorously with vegetable crops as an early-spring germinator. Mechanical weeding before seed set is the usual control method — the wind-pollinated, dioecious species produces large amounts of readily germinable seed.
Mercurialis annua is SLIGHTLY TOXIC when taken internally — the plant contains saponins (especially the mercurialin glycoside), methylamine and trimethylamine (responsible for the characteristic 'bingelkraut fish smell' of the wilting plant), and tannins. Oral ingestion causes nausea, vomiting, abdominal pain, mild gastroenteritis and, in larger amounts, circulatory disturbance. Compared with dog's mercury (Mercurialis perennis), M. annua is somewhat less toxic but still NOT suitable for therapeutic use. Today there is NO modern medicinal application — historical uses (Hildegard, Dioscorides, medieval herbals) are obsolete. Livestock (horse, sheep, cattle) poisonings from grazing bingelkraut-rich meadows or hay are occasionally documented (haemolysis, bloody urine, lassitude). Risk of confusion with the more toxic Mercurialis perennis (perennial root, unbranched stem), with brooklime (Veronica beccabunga) and with Chenopodium species in the young stage — caution when foraging. Before dyeing experiments: wear gloves and keep splashes away from the eyes.
Internal use during pregnancy is STRICTLY CONTRAINDICATED. Historical sources attribute emmenagogue and abortifacient action to bingelkraut (Hildegard, medieval gynaecology) — saponins and methylamines can affect smooth muscle including the uterus. External contact with plant sap (e.g. during dye experiments) should also be avoided during pregnancy, as data on percutaneous absorption are lacking.
Internal use during lactation is CONTRAINDICATED — methylamines and saponins may pass into breast milk and cause nausea, vomiting and gastrointestinal irritation in the infant. Historical 'breast poultices' for milk stasis are obsolete and explicitly not recommended.
STRICTLY AVOID in children — children are more sensitive to saponins and methylamines than adults. Accidental ingestion of a few leaves while playing usually causes only nausea and vomiting, but larger amounts can lead to gastroenteritis and circulatory problems. If ingestion is suspected: rinse the mouth, give plenty of water, DO NOT induce vomiting, and contact a poison control centre.
Drug interactions
Herzglykoside (Digitoxin, Digoxin)
Saponins may theoretically increase intestinal absorption of cardiac glycosides and, through potassium losses (with repeated laxative use), raise sensitivity to digitalis — relevant clinical data are lacking; the risk is hypothetical but justifies a general avoidance.
Diuretika und Abführmittel
The laxative action of saponins can amplify potassium and water loss from other diuretics or laxatives — risk of electrolyte disturbance.
Antikoagulantien und Thrombozytenaggregationshemmer
If Mercurialis-induced haemolysis or mucosal irritation occurs, the risk of gastrointestinal bleeding is increased; clinically relevant in combination with warfarin, DOACs or aspirin.
Contraindications
- Pregnancy and lactation — emmenagogue/abortifacient tradition and passage of methylamines into breast milk (see above).
- Infants, toddlers and children up to 12 years — increased sensitivity to saponins, no paediatric safety data whatsoever.
- Inflammatory gastrointestinal disease (gastritis, IBS, Crohn's, ulcerative colitis) — saponins and tannins worsen mucosal irritation.
- Known sensitivity to Euphorbiaceae as well as haemolytic anaemia or glucose-6-phosphate dehydrogenase (G6PD) deficiency — saponins can destabilise the erythrocyte membrane.
- Confusion with perennial dog's mercury (Mercurialis perennis) during foraging — the latter is more toxic and has caused multiple severe human poisonings with haemolysis and acute renal failure.
- Any kind of internal self-medication (tea, tincture, fresh shoots as wild vegetable) — no modern indication, no efficacy evidence, clear risk-benefit imbalance.
Harvested part: flowering herb
- Time of day:
- For historical dye experiments (hermidin/chrysohermidin system): harvest in late morning during dry weather — the plant's water content is then good while the aerial parts most important for sap extraction are at their most vigorous. Process immediately: the blue pigment is only generated by cell disruption and atmospheric oxidation, so crush and press the whole plants without delay. For plant identification and herbarium work, early and late summer months are favourable, when male and female plants (dioecious!) are clearly distinguishable in flower.
- Drying:
- Dyeing requires FRESH plant material — dried bingelkraut loses almost all its colouring power because the oxidation-sensitive hermidin system breaks down. For medical-historical collections or herbarium specimens the herb can be gently shade-dried at 30-35 °C; the dried drug is dull grey-green and almost odourless. Store dry, dark, wrapped in paper.
- Storage:
- 12 months — Dry, dark, airtight in paper or labelled jar. For collection and teaching purposes only — NOT for use as a medicinal drug. Fresh sap for dye experiments keeps for at most a few days refrigerated, after which pigment loss and mould develop.
- Time of day:
- Mechanical weed management in the garden: hoe or pull younger plants in May-June before seed set (main seed formation starts in July) — this prevents seeding of this dioecious, wind-pollinated species with its large seed output. In dry weather the hoed plants left on the soil surface desiccate rapidly; in moist weather it is better to remove them, as roots occasionally re-strike.
- Drying:
- Not applicable — plant material from weed control is composted (when in purely vegetative phase, before seed set) or disposed of via residual waste (if seeds have already formed) to prevent further spread in the garden.
- Mercurialin (Saponin-Glykosid)SaponinAerial parts
Characteristic saponin glycoside of the genus Mercurialis; responsible for much of the plant's mild toxicity and laxative properties. Mucosa-irritating, haemolytic at higher concentrations. Mercurialin is not strictly species-specific — it also occurs in M. perennis, though at higher concentration.
- TrimethylaminOtherAerial parts
Volatile aliphatic amine released when the plant wilts or is crushed — cause of the characteristic 'bingelkraut smell' reminiscent of rotten fish. Contributes to mucosal irritation; inhaled in small amounts harmless, but in enclosed spaces with large quantities of fresh plant unpleasant to nauseating.
- MethylaminOtherAerial parts
Companion volatile amine alongside trimethylamine, also from the plant's nitrogen metabolism. Contributes to the odour and shares responsibility for the mild mucosal toxicity. Methylamine is also a normal metabolic intermediate in the human body, but locally irritating at the quantities encountered here.
- Hermidin / Chrysohermidin (Phenanthren-Chinon-System)OtherAerial parts
Colour-defining key system of the plant. In intact living tissue, colourless hermidin (a reduced phenanthrene derivative) is present; on cell disruption it is enzymatically and atmospherically oxidised via several quinone intermediates to deep-blue to violet chrysohermidin. This transition is the chemical basis of the historic dye tradition ('tournesol des teinturiers'). The dye is strongly light-sensitive — historically suitable only for cheese marking, sugar loaves and ephemeral textiles.
- Gerbstoffe (Lamiaceen-untypisch, hier Ellagitannine + Catechine)TanninContent: 1-3 %Aerial parts
Astringent polyphenols, mainly ellagitannins and catechin derivatives; contribute to the mild mucosal irritation on internal use and provide part of the ethnobotanically described 'astringent action' for external poultices. Quantitative data are sparse; figures from older pharmacognostic literature (Madaus) lie in the low single-digit per cent range of dry weight.
- Flavonoide (Rutin, Quercetin-Glykoside)FlavonoidLeaf
Ubiquitous flavonoid companions in the leaves; contribute to baseline antioxidant capacity. In M. annua they are pharmacologically unremarkable — the plant is used neither as an antioxidant herbal drug nor as a flavonoid source. They do contribute to the yellow-green inherent colour of the dried herb.
- Ätherisches Öl (Spuren)Essential oilContent: <0.1 %Aerial parts
Only traces of an essential oil are present — compared with classical aromatic plants (sage, thyme), M. annua is almost odourless when fresh. The typical 'bingelkraut smell' on wilting does not come from the essential oil but from the released methylamines.
- [3]MonographPlants for a Future: Mercurialis annua — Annual Mercury(accessed: 2026-05-27)
- [7]MonographCardon, D. (2007): Natural Dyes — Sources, Tradition, Technology and Science. Archetype Publications, London. Chapter on Mercurialis-based 'tournesol' dye (ISBN 978-1-904982-00-5).(accessed: 2026-05-27)
- [8]MonographSwain, T. & Bell, E.A. (1976): Hermidin and chrysohermidin — pigment chemistry of Mercurialis. In: 'Chemistry in Botanical Classification', Nobel Symposium 25, Academic Press.(accessed: 2026-05-27)
- [9]MonographFloraWeb (Bundesamt für Naturschutz): Mercurialis annua L. — Verbreitung, Ökologie, Zeigerwerte(accessed: 2026-05-27)
- [10]MonographInfo Flora (Schweiz): Mercurialis annua L. — Artportrait, Ökologie, Häufigkeit(accessed: 2026-05-27)
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- [1]WikipediaEinjähriges Bingelkraut (Wikipedia DE)(accessed: 2026-05-27)
- [2]WikipediaMercurialis annua (Wikipedia EN)(accessed: 2026-05-27)