Small tufted herb with deep taproot ± 5 mm. diam. at crown and ∞ radical lvs; stolons or rhizomes few to many, forming offset plants at nodes, the whole forming patches up to ± 3 dm. diam. Radical lvs rosulate, ± 5-15 cm. long, subfleshy, coriac., pale green to glaucous, lanceolate to oblanceolate to spathulate in outline; margins ± undulate; deeply, coarsely toothed or lobed; teeth c. 5 mm. long, spinous. Cauline lvs similar, smaller, often 3-lobed. Peduncles rigid, up to c. 5 cm. long; umbels up to 2 cm. diam., ± 15-20-fld; fls subsessile, crowded. Calyxtube us. densely scaly, petals white. Involucral bracts lanceolate to linear, exceeding heads, spinous. Fr. ovoid, ribs obscure.

2n = 64

n = 32

Tufted perennial, with stolons or rhizomes, forming patches up to c. 30 cm diam. Basal lvs of 2 forms; winter lvs entire, fistular, septate; summer lvs lanceolate to ovate or spathulate, long-petiolate, deeply spinose-serrate and often undulate, c. 5-12 cm long; non-rosette lvs similar but reduced. Capitula solitary on short peduncles lateral to stolons or arising from rosettes, 5-10 mm diam.; bracts 6-9, triangular, 5-7 mm long; bracteoles similar to bracts but smaller. Fls many, white, 1-3 mm diam.; calyx teeth c. 1 mm long. Fr. scaly.