Strongly foetid annual herb. Stems erect or ascending, (5)-30-40-(60) cm tall, striate, almost glabrous to moderately hairy especially above, usually much-branched from base, rooting in lower part. Basal and lower cauline lvs apetiolate, ovate to obovate-oblong, glabrous to sparsely hairy and glandular, 3-pinnatisect, up to 8 cm long; ultimate segments subulate to linear, entire, not all in one plane giving a somewhat feathery appearance to the lf; cauline lvs similar to basal, smaller and less divided near capitula, usually ovate-oblong. Involucral bracts glabrous to moderately hairy, 2-6 mm long; margins and apex of at least inner bracts membranous. Capitula solitary, c. 15-30-(35) mm diam.; ray florets 8-21, very rarely 0; ligules white, becoming reflexed; disc florets numerous, yellow. Scales usually confined to inner ⅔ of receptacle, linear, acute. Achenes 1.3-1.7 mm long, obconic, narrowed slightly at apex, circular in section, brown, obscurely ribbed; ribs usually prominently tuberculate, rarely whole achene almost smooth; pappus 0.