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.