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DescriptionRobust, erect annual or perennial herb, 20-200 cm tall. Stems solitary, branching near the inflorescence, hollow, ribbed to angular, mostly hairless, sometimes glandular hairy above. Leaves with basal lobes conspicuously clasping the stem, more or less oblanceolate in outline, hairless, more or less glaucous; margins with irregular, sometimes lobe-like, spine-tipped teeth. Capitula stalked, forming corymbose clusters. Involucre often swollen at the base. Florets numerous, yellow, with rays up to 4 mm long.