Horrible weed or miracle herb?: A review of Bidens pilosa

Patrice Connelly B. Nat Therapies (SCU), Dip. Nutrition, is a nutritionist, energetic healer and musician practising in Kilcoy, Qld. PO Box 272, Kilcoy QLD 4515. Telephone (07) 5422 0806. patrice@saraband.com. au. Amember of the Asteraceae family, the weed Bidens pilosa Linn. is found throughout the world, probably originating in South America. First noted in Linneus’s Species Plantarum (1753), this weed has acquired a variety of common names: cobblers pegs, grab-a-leg, Spanish needles, pitchforks, stickybeak, hairy tickweed and many more. When it was introduced to Australia is unknown, but it is now prevalent in the Northern Territory, South Australia, Queensland and New South Wales, and is a major crop weed, outcompeting native species in tropical areas. B. pilosa is an erect annual which grows to an average height of 60 cm although it can reach 2 m in favourable conditions. The leaves are opposite and divided into three to five lanceshaped segments with serrated edges. Bright green whilst young, leaves can develop tinges of red and brown on maturity. Flowers are mostly yellow but can have white elements (ray florets) which can be present for periods of the flower’s development. The seeds are black or dark brown, slender and about 1cm long, clustered on the end of the stalk. They possess three tiny prongs at one end, which adhere to clothing and animals. There are several varieties of B. pilosa. One, B. pilosa Linn var. radiata, which is found in tropical America and Japan, has been analysed and shown to contain active constituents including flavonoids, polyacetylenes, flavone glycosides, chalcones, aurones and phenylpropanoids. B. pilosa also contains calcium, iron and zinc, as well as beta-carotene . Recent research is showing a useful side to this plant. Searches of ProQuest, CINAHL, Wiley Interscience and PubMed databases showed a number of papers observing significant health benefits of B. pilosa as a botanical medicine. Very few of the papers on this herb concerned testing on humans; most used rodents or performed in vitro experiments on cultured cell lines. It is obvious that a large amount of research remains to be performed on B. pilosa. This article will review fifteen of the papers, examining the potential health benefits from its use as a herb. B. pilosa has been used as a folk remedy in many third-world countries for eons. Wounds, colds and flu, fever, hepatitis and jaundice, glandular sclerosis, rheumatic conditions, neuralgia, smallpox, colic, diarrhoea, diuretic, pain, snake bite, conjunctivitis, anaemia, haemorrhage and rectal prolapse are just a few of many traditional uses of this herb . The body of serious research on B. pilosa has grown over the last decade. As the trend towards evidence-based medicine became more pronounced, research on this herb began as an attempt to validate its traditional use. In the process, a number of studies have shown its potential as an antimalarial , anticancer , antidiabetic, anti-inflammatory and antiallergy 18, , antihypertensive and smooth muscle relaxant , antimicrobial/antiviral (including herpes) , antipyretic, oxytocic, and nutritive 5, . As noted above, most intensive research on this herb is in its infancy, but these studies show promise for the use of B. pilosa as a possible complement or alternative to pharmaceutical drugs for the early stage of some of these conditions.