Aromatic herb. Stems erect or ascending, 5-20-(40) cm tall, striate, glabrous or with a few hairs below capitula, usually much-branched from base. Basal and lower cauline lvs appearing shortly petiolate but usually with very reduced leaflets along sheath, narrow-obovate to elliptic, usually glabrous, sometimes sparsely hairy when young, 2-3-pinnatisect, 2-8 × 0.5-2 cm; ultimate segments narrow-linear or subulate, ± all in one plane; cauline lvs similar to basal but above becoming smaller, with fewer segments, ovate, and apetiolate. Corymb diffuse, of 1-many capitula. Involucral bracts glabrous, 3-5 mm long; margins pale, membranous. Capitula 4-10 mm diam.; ray florets 0; disc florets numerous, dull yellow to greenish yellow, 4-toothed. Achenes c. 1.5 mm long, very pale brown, narrow-obovoid; inner surface with usually 4 narrow ribs, the outer 2 with glandular groove for > 1/2 length; outer surface smooth; corona < 0.1 mm long or 0.