Bidens pilosa L.
cobblers' pegs
Erect annual or short-lived perennial, 10-100 cm tall. Stems glabrous or sparsely hairy, ribbed, much-branched. Lvs glabrous to moderately hairy especially below, ciliate, petiolate, usually 3-foliolate with terminal leaflet larger, sometimes simple and not lobed to 3-lobed; leaflets sessile or shortly petiolulate, ovate to lanceolate, evenly serrate, acute to acuminate, (1)-2-10-(25) cm long. Upper cauline lvs becoming smaller, shortly petiolate, and more often simple and not lobed or 3-lobed. Capitula c. 6-10 mm diam. Outer involucral bracts 7-9, foliaceous, ciliate, linear to narrowly oblong-obovate, 3-6 mm long; inner bracts many, membranous, triangular to subulate, 4-6 mm long, with dark lined centre and pale margins. Receptacular scales similar to inner bracts but narrower. Florets usually all ⚥, tubular, yellow-orange, sometimes c. 5 white ray florets present. Achenes flattened or 3-(4)-angled, ± linear, ribbed, dark brown, usually glabrous except for ribs ciliate near apex, sometimes with scattered hairs elsewhere, 5-9 mm long; awns mostly 3, sometimes 2, rarely 4, sometimes unequal, (0.5)-1.5-2.5 mm long.
N.: south to Bay of Plenty, including many offshore islands; K.: Raoul Id.
Tropical and subtropical, origin uncertain 1832
Waste places, coastal sites, forest margins and clearings.
FL Aug-May-(Jul).
Cobblers' pegs is a cosmopolitan weed which has sometimes been considered indigenous to N.Z. However, it is most probably an early Polynesian introduction (see, Sykes 1977) which is now established in many apparently undisturbed communities. Sherff (op. cit.) provided a complex intraspecific classification for B. pilosa largely based on characters which vary within populations; that classification is not accepted here. Within N.Z. material, plants from K. differ from those of the North Id and offshore islands in more often having larger, simple lvs, and in the greater frequency of 2-awned achenes; this may indicate 2 introductions to N.Z. B. pilosa is easily distinguished from the other 2 spp. in N.Z. by the narrow achenes (Fig. 21). It has previously been referred to in N.Z. as B. aurantiacus and B. bipinnatus.
