Strongly scented, rhizomatous herb, with short non-flowering rosettes often forming dense mats. Stems usually erect, sometimes ascending, up to c. 80 cm tall, ribbed and striate, hairy especially above, usually not branched except above to form infl. Basal lvs petiolate, lanceolate, moderately hairy, 2-pinnate with segments again 1-2-pinnatisect, 6-15-(44) × 1-2-(4) cm; primary leaflets in 18-30-(37) pairs; ultimate segments subulate, not all in one plane giving a feathery appearance to lf; rachis c. 1-2 mm diam., flattened, sometimes slightly winged, not toothed. Cauline lvs similar to basal, but above becoming apetiolate, less divided, smaller, and with fewer leaflet pairs. Corymbs usually ± flat-topped or slightly convex, to c. 15 cm across, with numerous, closely packed capitula. Involucral bracts glabrous to sparsely hairy, 1.5-4-(5) mm long; margin brown, hairy. Capitula (3.5)-5-10 mm diam.; ray florets 4-7; ligule and disc florets usually white, sometimes pink to deep red or purple. Achenes grey-brown, c. 2 mm long; wings narrow, pale brown.