Xanthium strumarium L.
Noogoora bur
Erect annual, up to c. 1 m tall. Stems sparsely to moderately hairy above, becoming glabrous below, usually branched. Lvs long-petiolate, spineless; lamina green with with scattered short, scabrid, hairs and glands on both surfaces, broad-ovate, irregularly serrate, 3-lobed or not lobed, cordate or truncate at base, 5-15 cm long; uppermost lvs smaller and narrower. ♂ and ♀ capitula in axillary or terminal clusters; ♀ sometimes solitary; ♂ with numerous florets. Fruiting involucre sparsely to moderately scabrid, sometimes almost glabrous at maturity, 15-25 × 8-20 mm; prickles hooked, glabrous or hairy, 3-5 mm long; beaks 2, conspicuous, 4-6 mm long.
N.: recently collected from the Waikato (Matamata and vicinity of Cambridge), also known from one early collection from Wellington City.
N. temperate regions, C. and S. America 1894
Cultivated land.
FL Jan-Mar, FR Mar-Aug.
X. strumarium is an enormously variable sp. divided into many minor intraspecific, interfertile entities (Löve and Dansereau, op. cit.). Even within the limited material collected in N.Z., there is considerable variation in the size and hairiness of burs, the density of prickles, and the extent to which the beaks are hooked; this probably reflects separate introductions as seed impurities. Many of the intraspecific entities have previously been treated at sp. rank; names formerly used in N.Z. and now placed in synonomy are X. cavanillesii, X. chinense, X. occidentale, and X. pungens. In spite of the remarkable variation in the burs of X. strumarium, they are easily distinguished from those of X. spinosum by the much longer beaks (Fig. 25).
