Common names (selected) English: beggar tick, beggar ticks, beggarticks, blackjack, bur marigold, cobbler's pegs, duppy needles, farmer's friend, hairy Spanish needles, needle grass, spanish needle, stick tight; Chinese: 大花咸豐草 (large flower); Hawaiian: ki, ki nehe, ki pipili, kookoolau, nehe, pilipili, Portuguese: amor-de-burro, picão (Portugal), amor seco, carrapicho-de-duas pontas, coambi, erva-picao, fura-capa, goambu, picao, picao preto, picao-campo, pico-pico (Brazil); Spanish: apestosa (Honduras), manzanilla del pais (Bolivia); papuga, picon, romerillo blanco (Cuba); rosilla grande (Honduras); amor seco, espina de erizo, picón, saetilla (Argentina); asta de cabra, cacho de cabra (Chile); cadillo, chipaca, masquia, papunga chipaca (Columbia); margarita silvestre, romerillo (Dominican Republic); amor seco, cadilla; pega-pega; perca (Peru); acahual, acahual blanco, aceitilla, aceitilla blanco, aceitillo, amapola, amor seco, cadillo, China, cruceta, é de milpa, hierba amarilla, hierba del pollo, iztacmozot, kutsúmu (purépecha), mozoquelite, mozote, mozote blanco, mozotl, quelite amargo blanco, rocía, rocilla, rosilla, saetilla, sepé, sepeke (tarahumara), stuyut, té de milpa blanco, te de playa, tutuk joi'dha (tepehuán), zetya (Mexico), jacalate, vara de jacalate (Spain); Philippines: dadayem, nguad, panibat, pisau-pisau, puriket, purpurikit, tagab, tubak-tubak
Description: Herbaceous perennial. B. pilosa seeds can remain viable for 3 years when buried below the soil surface. It is a fast-growing plant that can produce 3000 – 6000 seeds. B. pilosa prefers full sun and moderately dry soil, however, it can grow in arid and barren land from low to high elevations. The phenomenal spread of Bidens species in general is due partly to their effective pollination mechanisms and distinctive dispersal adaptations, which allow seed distribution by humans, animals, wind and water.
Native regions and distribution: B. pilosa is native to Southwestern US, Mexico, Carribean, Central and South America but is now a pantropical weed, recorded as invasive in 46 countries and islands.
Urban habitat: It is often seen as a weed in crops, pastures, gardens, as well as growing along roadsides and in other neglected areas.
Ecological functions: Food and habitat for insects and birds.
History / human uses: The name Bidens is derived from the Latin bi (two) and dens (teeth) referring to the prominent barbed awns projecting from the apex of each seed. Pilosa, refers to the downy hairs on the stems and the leaves. B. pilosa has a long history of human use, as a beverage, pesticide, and medicine to treat a wide variety of maladies. It has been reported to possess effective pharmacological properties, as an antibacterial, anti-inflammatory, antiallergic, and antimalarial. It has also been reported that extracts or compounds of the plant have antitumor, antidiabetic and antihyperglycemic, anti-oxidant, antifungal, antihypertensive, and anti-rheumatic activities. Examples of its use around the world include: In China, it is used to treat asthma, colic, conjunctivitis, dysentery, influenza, intestinal problems, nose bleeds, snake bite, sore throat, and is used as an anti-inflammatory. In Taiwan, it is used to treat diabetes. In Hong Kong, it is used to treat appendicitis, hepatitis, and rheumatism. In the Peruvian Amazon, it is used for aftosa, angina, diabetes, dysentery, dysmenorrhea, edema, hepatitis, jaundice, laryngitis and worms. In Piura, a decoction of the roots is used for alcoholic hepatitis and worms. The Cuna tribe mixes the crushed leaves with water to treat headaches. In other parts of the Amazon, a decoction of the plant is mixed with lemon juice and used for angina, sore throat, water retention, hepatitis, and dropsy. It is increasingly being cultivated as a leafy vegetable, mainly in southern Africa.