Hairy beggarticks
Bidens pilosa L.
Bidens pilosa (hairy beggarticks), also called black-jack, is an aster-family annual herb 30–100 cm tall; its small flower heads have white ray florets and yellow disc florets, and its barbed fruits stick to clothing — a common weed throughout the tropics.
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Gallery
Bidens pilosa — ripening fruitBidens pilosa — whole plant
Bidens pilosa — flower head
Bidens pilosa — flower head (close-up)
Bidens pilosa — fruits
Bidens pilosa — seedsBidens pilosa — ripening fruitBidens pilosa — whole plantOverview
Bidens pilosa (hairy beggarticks), also called black-jack, is an **annual** herb of the aster family (Asteraceae), genus Bidens, 30–100 cm tall, with **erect, branched, hairy stems**. Its **leaves are opposite**, usually **pinnately compound** with 3–7 ovate-lanceolate leaflets with toothed margins. The **flower heads (capitula)** grow singly or a few at the tips: each head has **white ray florets** (usually 4–7) and **yellow disc florets** in the centre. The **fruit is an achene (cypsela)** bearing 2–4 barbed awns, so it easily **clings to clothing and animal fur** — the hallmark of beggarticks.
Updated by lebachungtdh@gmail.com · 10/13/2026
Bidens pilosa is native to tropical America and is now a **cosmopolitan weed** of tropical and subtropical regions, spreading fast on open ground, roadsides, fields and gardens. In folk medicine the **whole plant** is used for sore throat, fever and infections, and in some places young shoots are eaten as a vegetable. Its barbed fruits cling to clothing and animal fur, aiding dispersal. It has not been assessed by the IUCN and is therefore listed as Not Evaluated (NE).
Updated by lebachungtdh@gmail.com · 10/13/2026
Life cycle
From seed to productGermination & seedling
Seeds germinate on moist soil; seedlings grow fast, becoming branched young plants within weeks.
Growth (stem & leaves)
The plant grows tall and branches; **opposite, pinnately compound leaves** have 3–7 toothed leaflets.
Flowering
**Flower heads** with **white ray florets** (4–7) and **yellow disc florets** in the centre; attractive to bees and butterflies.
Fruit & dispersal
Ripe achenes bear **2–4 barbed awns** that cling to clothing and animal fur, aiding dispersal.
Distribution & origin
Share of recorded occurrences by region- Tropical America (native)30%
- Southeast Asia (introduced)20%
- Africa (introduced)20%
- South Asia & Oceania15%
- Elsewhere (introduced)15%
Chemical composition
Relative content in agarwood resin- FlavonoidsContribute to antibacterial and anti-inflammatory effects25%
- Essential oil (terpenes)Gives the characteristic strong aroma20%
- PolyacetylenesCharacteristic bioactives of the genus Bidens15%
- TanninsPresent in stems and leaves15%
- Terpenoids/steroidsSecondary components15%
- Minerals & vitaminsK, Ca, vitamin C, etc.10%
Uses
- Folk medicine: the **whole plant** is used for sore throat, fever and inflammatory complaints in many countries.
- Food: in some places the **young shoots and leaves** are boiled and eaten as a vegetable.
- Fodder: the plant is used as feed for livestock and poultry.
- Nectar: the flowers provide nectar and pollen for bees and butterflies.
- Caution: it is an invasive weed; the barbed fruits cling to clothing and animal fur.
Properties
- Morphology
- Erect branched stems; **opposite, pinnate leaves**
- Flowers & fruit
- White-and-yellow heads; barbed fruit sticks to clothing
- Ecology
- Light-loving, fast-growing, flowers and fruits year-round
- Medicinal
- Used in folk medicine for sore throat, fever and inflammation
Habitat & conservation
Bidens pilosa is light-demanding and very tolerant, spreading quickly on disturbed ground: open land, roadsides, abandoned fields, gardens, pastures and field margins throughout the tropics and subtropics. Native to tropical America, it has become an almost cosmopolitan weed.
Conservation
Bidens pilosa is not threatened; it is a common weed, sometimes regarded as a weed to be controlled in agriculture. It has not been assessed by the IUCN and is therefore listed as Not Evaluated (NE). Family Asteraceae, genus Bidens. Value: folk medicine, edible herb and fodder.
References
- 1POWO — Bidens pilosa L. — Plants of the World Online (Kew), 2026
- 2GBIF Backbone Taxonomy — Bidens pilosa L. (key 5391845) — GBIF, 2026
- 3Wikipedia EN — Bidens pilosa — Wikipedia EN, 2026
- 4Wikipedia VI — Đơn buốt — Wikipedia VI, 2026
- 5Wikipedia ZH — 鬼针草 — Wikipedia ZH, 2026
- 6Ảnh: Bidens pilosa 3 (CC BY-SA 3.0); closeup; hairy beggarticks macro (CC BY 4.0) — Wikimedia Commons — Wikimedia Commons, 2026
- 7Ảnh: Chogoria cypselas (CC BY-SA 4.0); seeds (PD); ripening infructescence — Wikimedia Commons — Wikimedia Commons, 2026