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Scale bar 10mm. Copyright CSIRO
Cotyledon stage, epigeal germination. Copyright CSIRO
10th leaf stage. Copyright CSIRO
Bidens bipinnata L.
Linnaeus, C. von (1753) Species Plantarum 2: 832. Type: Habitat in Virginia..
Beggar's Ticks; Spanish Needles; Beggarticks; Bipinnate Beggar's Ticks
Usually flowers and fruits as a herb but occasionally flowers as a shrub 1-1.5 m tall.
Twigs or stems 4-angled in transverse section. Leaf blades about 8-14 x 3.8 cm, usually pinnate, bipinnate or bipinnatisect. Both the upper and lower surfaces of the leaflet blades clothed in white prostrate hairs.
Flowers borne in heads 5-10 mm diam., 30-40 flowers per head. Outer flowers very zygomorphic and sterile. Flowers surrounded or subtended by persistent pubescent bracts, the outer ones recurved and the inner ones incurved. Calyx reduced to short hairs and 2-3 bristles with recurved spines. Anthers fused together, filaments free. Pollen orange.
Each fruit or nutlet ending in 2-3 plumes each with downward pointing hairs which adhere to clothes, animal fur, etc. Fruits about 9-26 mm long. Seeds about 6-12 mm long. Embryo about 6-8 mm long, cotyledons about 2/3 of the length of the embryo. Cotyledons wider than the radicle.
Cotyledons +/- linear or linear-falcate, about 15-20 x 2 mm, curved in opposite directions like a propeller. First pair of leaves opposite, bipinnate, lobed or deeply lobed, each lobe apiculate. At the tenth leaf stage: leaves +/- bipinnate and/or deeply lobed, each lobe apiculate. Midrib raised on the upper surface of the leaflet blades. Stems longitudinally ribbed.
Distribution and Ecology
A cosmopolitan species of uncertain origin, now naturalized in WA, NT, CYP and NEQ and southwards to south-eastern Queensland and north-western New South Wales. Altitudinal range from near sea level to 600 m. Grows in monsoon forest, vine thickets and other vegetation types.
This species may have some medicinal uses. (http://www.ibiblio.org/herbmed/eclectic/kings/bid ens.html)
Herb (herbaceous or woody, under 1 m tall)
Shrub (woody or herbaceous, 1-6 m tall)