Centaurea solstitialis L.
yellow star thistle
Biennial. Stems suberect to erect, weakly ribbed, branched, (10)-25-80 cm tall, with lanate to floccose tomentum. Lvs decurrent to form wings on stems, lanate; lower lvs pinnatifid, 6-12 × 1-3 cm, with triangular, oblong or linear, sinuate or lobed segments; upper lvs linear-lanceolate to narrowly triangular, entire or sinuate or toothed. Capitula not clustered. Involucre ovoid, (5)-7-12 mm diam.; outer and middle bracts ovate, not veined, with cobwebby hairs; appendages spreading to reflexed, not covering bracts, spinous, not narrowed at junction with bract, not decurrent on bract; terminal spine 15-25 mm long, shorter on outermost bracts, yellowish; lateral spines 2-(3) on each side, (1)-2-4 mm long, all at base of terminal spine. Florets yellow, all tubular. Corolla eglandular. Achenes 2.5-3 mm long, glabrous; pappus 3-4 mm long.
S.: Nelson (Sherry R.), Canterbury, Otago.
S. Europe, S.W. Asia 1872
Pasture and cultivated land, usually in dry habitats.
FL Dec-May FT Jan-May.
Of the Centaurea spp. naturalised in N.Z., only C. solstitialis and C. melitensis have both yellow florets and spinous bracts; the 2 spp. were frequently confused in early records. C. melitensis differs in having 1 pair of lateral spines borne ⅓ of the way up the terminal spine, a corolla with glandular papillae, and in having short curved hairs rather than a lanate indumentum on the lvs. C. calcitrapa also has spinous bracts, but has a purple, glandular corolla and lvs not decurrent on the stems.
