The Ubiquitous Black-Jack with Surprising Medicinal Virtues.

Description

Often dismissed as a common garden weed due to its tenacious, sticky seeds, Bidens pilosa is a plant of profound global medicinal importance. Found on almost every continent, this resilient herb has been independently incorporated into the traditional medicine systems of cultures from Africa to South America and Asia. Bidens pilosa is an annual herbaceous plant that is easily recognizable by its seeds rather than its flowers. It can grow erect or sprawling, typically reaching heights between 30 cm and 1.5 meters. The stem is often green with purple streaks and may be hairless or slightly hairy. The leaves are compound and oppositely arranged on the stem. They are typically trifoliate, meaning each leaf is divided into three ovate to lance-shaped leaflets with serrated (toothed) margins. The terminal leaflet is the largest. The flower heads are small (about 1 cm in diameter) and consist of two types of florets: central, tubular, yellowish-brown disc florets surrounded by a fringe of 4-5 white (or sometimes absent) ray florets. They are not particularly showy. The most distinctive feature is the fruit, a narrow, dry, barbed achene. Each achene is topped with 2-4 backward-pointing bristles (the “pilosa” refers to these hairs). These barbs easily attach to animal fur, feathers, and human clothing, earning it the common name “beggar’s ticks” or “black-jack,” as they are notoriously difficult to remove.

Other Names

  • English: Black-Jack, Hairy Beggarticks, Cobbler’s Pegs, Spanish Needle, Farmer’s Friends
  • Spanish: Amor seco, Mozote
  • Portuguese: Picão-preto, Carrapicho
  • South Africa: Blackjack (Afrikaans/English)
  • Yoruba: Esin Jẹjẹ
  • Kikuyu (Kenya): Mũcenjerere
  • Chinese: Gui Zhen Cao (Ghost Needle Grass), Xian feng cao (仙峰草)
  • Hawaiian: Kī, Nehe
  • Brazil: Picão
  • English: Spanish needle, Blackjack, Beggar’s tick, Cobbler’s peg
  • Yoruba: Ẹfọ ajeri
  • Igbo: Agwọ-nkịlị-ụkwụ
  • Hausa: Zuma-zuma
  • Swahili: Mnyasi-chafua nguo

Health Benefits

The medicinal properties of Bidens pilosa are linked to its rich and diverse phytochemical composition including over 200 identified compounds like phenylheptatriyne, quercetin, polyynes, flavonoids, tannins, and phenolic acids. Modern research is actively investigating its traditional uses.

  • Anti-inflammatory and Analgesic Properties: Extracts from the plant are widely used to reduce inflammation and relieve pain associated with conditions like arthritis, rheumatism, headaches, and toothaches.
  • Antimicrobial and Wound Healing Properties: Its antimicrobial activity combats bacteria (e.g., Staphylococcus aureus, Escherichia coli), fungi (e.g., Candida albicans), and parasites like Plasmodium, aiding in wound healing, skin infections, and malaria treatment. The crushed leaves are applied topically to wounds, ulcers, and boils.
  • Gastrointestinal Aid: It is a common remedy for a wide range of digestive issues. Decoctions are used to treat stomach ulcers, diarrhea, dysentery, and abdominal pain. It is also used as a vermifuge to expel intestinal worms.
  • Hepatoprotective (Liver-Protecting) Effects: Research has shown that extracts can protect the liver from damage caused by toxins and may be beneficial in managing hepatitis and jaundice.
  • Antidiabetic Potential: Several animal studies have indicated that Bidens pilosa may help lower blood glucose levels, supporting its traditional use for managing diabetes.
  • Immunomodulatory Activity: Compounds in the plant have been shown to modulate the immune system, which can be beneficial for managing immune-related disorders.
  • Treatment of Malaria and Fever: In many African traditions, it is used as a remedy for malaria and to reduce fever.
  • Antioxidant properties: With high phenolic content (e.g., TPC up to 85 mg GAE/g), protect against oxidative stress, potentially mitigating diabetes, cardiovascular diseases, and aging-related disorders.
  • Anticancer Properties: The anticancer activity is driven by polyacetylenes which inhibits tumor growth in cancers like breast, liver, and colon
  • Respiratory relief: Helpful for cough, flu, and sore throat.
  • Liver support: Helps detoxify and protect the liver.
  • Other Health Benefits: Other uses include treating respiratory issues (coughs, colds), gastrointestinal disorders (diarrhea, dysentery), liver conditions (hepatitis), and skin ailments (wounds, eczema). It also serves as an analgesic for headaches and a diuretic for urinary issues

Other Benefits

Beyond its medicinal value, Bidens pilosa has other practical applications:

  • Food Source: The young leaves and shoots are edible and are consumed as a leafy green vegetable, raw in salads, or cooked in soups and stews in many parts of Africa and Asia. They are a good source of vitamins and minerals.
  • Agricultural Uses:
    • The plant is used as forage for livestock.
    • The extracts serve as natural biopesticides, repelling pests like aphids and mosquitoes due to polyacetylenes, and inhibiting fungal pathogens in crops.
  • Ecological Indicator:
  • Its presence often indicates disturbed, nitrogen-rich soils.
  • The plant contributes to soil fertility as green manure and supports ecological restoration in degraded areas by stabilizing soil.<
  • Its allelopathic properties suppress competing weeds, benefiting crop growth in intercropping systems.
  • Cultural Uses: It is used in traditional rituals and as fodder for livestock in some regions.

How It Is Used

The leaves, stems, and roots are used, with preparations varying by region and the ailment being treated.

  • Topical Poultice: Fresh leaves are crushed and applied directly to wounds, boils, burns, and inflamed joints. The sap from the stem can be applied to cuts to stop bleeding.
  • Decoction and Tea: The most common method for internal use. The whole plant or its parts are boiled in water. This liquid is drunk to treat malaria, fever, digestive problems, diabetes, and liver issues.
  • Juice: The fresh plant is pounded and the expressed juice is taken orally, often for liver disorders or as a general tonic.
  • Culinary Uses: The young, tender leaves are harvested and cooked as a nutritious green vegetable.
  • Tincture and Extracts: The plant material is macerated in alcohol or other solvents to create a concentrated liquid extract.
  • Oils and Smoke: Essential oils are applied for insect-repellent or antifungal purposes, and the plant is sometimes smoked in traditional practices for respiratory relief.
  • Topical wash: Decoction is used to cleanse skin rashes and wounds.

Side Effects and Caution

Bidens pilosa is generally safe at moderate doses, with acute toxicity studies showing no mortality at doses up to 5,000 mg/kg in animals. While generally considered safe when used in culinary amounts or appropriately in traditional medicine, some cautions exist.

  • Pregnancy and Breastfeeding: Due to a lack of safety data and its potential effects on uterine activity, its medicinal use should be avoided during pregnancy and breastfeeding.
  • Allergy: Individuals with allergies to plants in the Asteraceae/Compositae family (like ragweed, marigolds, daisies) may also be allergic to Bidens pilosa.
  • Dosage: High doses or prolonged use of concentrated extracts may lead to side effects. Overconsumption has been linked to potential liver toxicity in some animal studies, though this is often dose-dependent. Its polyacetylene content may lead to photosensitivity or liver stress at excessive doses.<
  • Hypoglycemic Effect: Diabetic patients on medication should use it with caution, as it may potentiate the effects of diabetes drugs and lead to hypoglycemia (dangerously low blood sugar).
  • Surgery: Due to its potential effect on blood sugar levels, it is advisable to stop using it at least two weeks before a scheduled surgery.
  • Drug Interaction: It may interact with medications metabolized by cytochrome P-450 enzymes, potentially altering drug efficacy, particularly for antidiabetic or antihypertensive drugs.
  • Overuse: Overuse in topical applications may cause skin irritation. Consult healthcare providers before use, especially for long-term or high-dose applications.

Reference

  • Andrade-Cetto, A., and Heinrich, M. Mexican plants with hypoglycaemic effect used in the treatment of diabetes. Journal of Ethnopharmacology, vol. 99, no. 3, 2005, pp. 325–348.
  • Bartolome, Arlene P., et al. “Bidens pilosa L. (Asteraceae): Botanical Properties, Traditional Uses, Phytochemistry, and Pharmacology.” Evidence-Based Complementary and Alternative Medicine, vol. 2013, 2013, article 340215, doi:10.1155/2013/340215.
  • Bidens pilosa L. Plants of the World Online, Royal Botanic Gardens, Kew, www.plantsoftheworldonline.org/taxon/urn:lsid:ipni.org:names:185018-2. Accessed 5 Sept. 2025.
  • Dimo, T., et al. Leaf Extract of Bidens pilosa Prevents and Reverses Hyperglycemia in Experimental Diabetes. Journal of Ethnopharmacology, vol. 115, no. 3, 2008, pp. 419-23.
  • Iwu, Maurice M. Handbook of African Medicinal Plants. 2nd ed., CRC Press, 2014.
  • Okoye, T. C., et al. Bidens pilosa Linn.: Phytochemistry, pharmacological activities, and toxicological evaluation. Journal of Ethnopharmacology, vol. 245, 2019, 112174.
  • Oliviera, F. de Q., et al. Wound Healing Activity of Bidens pilosa L. Extract. Pharmaceutical Biology, vol. 41, no. 6, 2003, pp. 426-31.
  • Pereira, R. L., et al. Antimicrobial Activity of Bidens pilosa L. (Asteraceae) against Gram-Positive and Gram-Negative Bacteria. Revista Brasileira de Plantas Medicinais, vol. 17, no. 6, 2015, pp. 1055-60.
  • Yankuzo, H., et al. Hepatoprotective Effect of Bidens pilosa L. (Asteraceae) Leaf Extract Against Carbon Tetrachloride-Induced Liver Damage in Rats. Journal of Ethnopharmacology, vol. 138, no. 3, 2011, pp. 741-44.
  • Yang, Hui-Ling, et al. Phytochemical and Pharmacological Profiles of Bidens pilosa: An Overview. Pharmaceutical Biology, vol. 58, no. 1, 2020, pp. 469–479, doi:10.1080/13880209.2020.1762669.