Citation: L., Sp. Pl. edn 2:1159 (1763).

Synonymy: Not Applicable

Common name: Stemless thistle, stemless onopordum, horse thistle.

Description:
Biennial herb, rosette-forming, with a large tap root; stem absent; leaves oblanceolate to elliptic, to 50 cm long, to 12 cm wide, pinnatifid to pinnatipartite with triangular lobes, with numerous yellowish spines to 1 cm long, densely grey-white-woolly on both surfaces.

Capitula solitary or clustered, sessile or on peduncles to 3 cm long in the centre of the rosette, 4-6 cm diam.; involucral bracts lanceolate, 2-3 cm long, acuminately tapered into a straight spine, glabrous, green, all erect or the outer series recurved; corolla 22-25 mm long, white.

Achenes compressed-obovoid, 4-ribbed, faintly wrinkled, 4-5 mm long; pappus bristles 2-3 cm long, buff, barbellate.

Published illustration: Cunningham et al. (1982) Plants of western New South Wales, p. 726.

Distribution:  Locally abundant weed of pastures, arable land and roadsides, chiefly on heavy soils. S.Aust.: FR, EA, EP, NL, MU, YP, SL, KI, SE.   W.Aust.; N.S.W.; Vic.   Native to Spain and southern France. Conservation status: naturalised Flowering time: Oct. — Dec.

SA Distribution Map based on current data relating to specimens held in the State Herbarium of South Australia

Biology: Two subspecies of O. acaulon are recognised in Europe; however, S.Aust. populations are not clearly refertable to either subspecies and may have been derived from both.

Author: Not yet available