Bidens pilosa L.
Bidens is the Latin word for 'two toothed' or 'two pronged fork' and refers to the fork shaped awns on the seeds.
Other Names:Burr Marigold
Summary:Slightly hairy or hairless, erect, course, annual herb, 300-2000 mm tall with angular stems, opposite leaves and 2-4 awns on the seeds.
Petiole - Hairy on the top side and margins. Clasps the stem. Long and slender.
Blade - Thin. Simple or compound, with leaflets on either side of midrib. 3-5 leaflets, 10-60 mm long, end leaflet is longer than the side ones. Leaflets sometimes have stalks, egg shape to lance shaped with toothed edges. Tip pointed. Base tapered. Top surface is rough to touch. Underneath they have stiff hairs on the main veins.
Stems: 300-2000 mm tall, angular. Hairless or with hairs that have crosswise partitions (septate).
Flower head:Few to numerous. White and yellow. On long slender stalks in panicles at the end of the stem. Floral bract set is 4-7 mm long, cylindrical, 6 mm diameter. Outer bracts are parallel sided and hairy, inner bracts are broader with pale edges and hairy near the top.
Flowers: Tubular. Disc florets are yellow. Ray florets small and white or absent.
Petals - few or absent.
Fruit:Achenes in clusters. Becomes black and rigid. Narrow and parallel sided. Striped. 6-12 mm long. Short stiff erect hairs on the top third. 3 or 4 angled lengthwise.
Seeds:2-4 erect, brown, barbed awns, 2-5 mm long.
Yellow or yellow and white daisy flowers.
Annual. It germinates in spring and summer after rains, is a dark green colour and flowers in late summer to autumn before dying.
Flowering times:Late summer to autumn.
Seed Biology and Germination:Vegetative Propagules:
Population Dynamics and Dispersal:
Seeds cling to clothing and wool.
Origin and History:South America, Tropical and sub tropical areas.
Distribution:ACT, NSW, NT, QLD, SA, VIC, WA.
Courtesy Australia's Virtual Herbarium.
Habitats:Warm climates. Prefers loam or clay loam soils.
Loam or clay-loam soils usually.
Plant Associations:Often occurs in clumps.
Medicinal uses in South Africa for rheumatism, diarrhoea and colic (Webb, 1948).
Detrimental:Burrs contaminate wool.
Major weed of tropical crops.
Weed of roadsides, pastures and disturbed areas.
May taint milk.
Stock tend to ignore it.
Management and Control:Thresholds:
Beggars ticks (Bidens bipinnata)
Greater Beggar's-ticks (Bidens subalternans)
Marigold Burr (Bidens tripartita)
Plants of similar appearance:References:
Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P86. Photo.
Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P876.
Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P368.
Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P665.
Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne). p???.
Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #173.2.
Webb L.J. (1948). Guide to the medicinal and poisonous plants of Queensland. Bulletin #232. Council for Scientific and Industrial Research. Melbourne.
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