Habit, leaves, flowers and fruit. Copyright CSIRO
Cotyledon stage, epigeal germination. Copyright CSIRO
Scale bar 10mm. Copyright CSIRO
10th leaf stage. Copyright CSIRO
Bidens pilosa L.
Linnaeus, C. von (1753) Species Plantarum 2: 832. Type: Habitat in America..
Bidens pilosa var. typica Domin, Bibliotheca Botanica 89(4): 1235(1928), Type: ?.
Spanish Needles; Beggar Ticks; Pitchforks; Cobbler's Pegs; Blackjack
Usually flowers and fruits as a herb but occasionally grows into a shrub 1 m tall.
Leaf or leaflet blades about 6-12 x 4-8 cm, only sparsely hairy on the underside. Petioles grooved on the upper surface, petiole bases forming a transverse ridge across the twig and this ridge resembles a stipular scar. Stems +/- 4-angled.
Flowers borne in heads about 5-15 mm diam., about 40-50 flowers per head. Flowers surrounded or subtended by persistent erect bracts with fimbriate margins. Pollen orange.
Each fruit or nutlet about 6-12 mm long, ending in about 3-5 plumes each with downward pointing hairs which adhere to clothes, animal fur, etc. Cotyledons longer than the radicle but of equal width.
Cotyledons +/- linear, about 13-22 x 2-4 mm. First pair of leaves either simple or deeply lobed or compound with three leaflets each of which is toothed or lobed. At the tenth leaf stage: leaves trifoliolate with the middle leaflet much longer than the lateral leaflets. Leaflets hairy on both the upper and lower surfaces.
Distribution and Ecology
A cosmopolitan species of uncertain origin, now naturalized in NT, CYP, NEQ and southwards as far as Victoria. Altitudinal range from near sea level to 1200 m. Grows in disturbed areas in rain forest.
This species has medicinal uses. (http://www.amazon-medic.co.uk/database/data/Picao preto.html)
An infusion of the plant, sometimes of the flower-heads only, has been used in domestic medicine in several countries for diarrhoea, dysentery and coughs; the tannin content provides an astringency which would be of some use in those complaints. Cribb (1981).
Herb (herbaceous or woody, under 1 m tall)
Shrub (woody or herbaceous, 1-6 m tall)