Erect or ascending perennial (sometimes annual in adverse conditions) to c. 30 cm high, new growth commonly resprouting from base, glabrous, or cottony near the growing tips, or rarely cottony overall. Leaves oblong or narrowly obovate, 7-30 mm long, 2.5-7 mm wide, serrate, glabrous, resin-dotted on both surfaces, concolorous or slightly paler below. Inflorescence a single sessile cauline capitulum, not leaf-opposed, often in branch axils. Capitula at anthesis biconvex, hemispherical or subglobular, 4-6(-8) mm diam.; involucral bracts 3-5-seriate, obovate, 1.5-3 mm long, entire or with minutely ruminate membranous margins, glabrous to lightly (rarely densely) cottony; receptacle strongly convex; female (outer) florets c. 200-350, in 7-12 rows, corollas narrowly cylindrical, 0.3-0.5(-0.7) mm long (including lobes c. 0.1 mm long); bisexual florets c. 20-50(-70), corollas funnel-shaped, 0.7-0.8 mm long (including lobes c. 0.3 mm long and wide), pale green, rarely tipped reddish. Fruiting heads usually remaining intact until stems senesce; bracts of fruiting heads widely spreading; fruiting receptacle 1.8-2.5(-3.5) mm diam., with a pith layer entirely contained within the dome of the receptacle; cypselas oblong, 1.2-1.6 (-2) mm long, truncate or rounded at apex, with 4 prominent ribs, occasionally with 1 or 2 minor ribs, the ribs smooth or scabridulous, united at or above three-quarters of the cypsela length into a thickened, spongy or corky apical portion, the pericarp between the ribs in the lower part normally very thin with the brown testa of the seed apparent; vesicular trichomes scattered over the faces of the cypsela between the ribs. Hairs on ribs antrorse (sometimes appressed), c. 0.1-0.2 mm long, usually tightly inrolled at their apices.

Ascending to erect, stout, aromatic, glabrous or very rarely sparsely hairy perennial. Stems terete, much-branched from base and above, (3)-10-60 cm long. Lvs glandular, oblong to oblong-spathulate, acute, narrowed to base but petiole usually indistinct, often slightly amplexicaul, coarsely toothed, (3)-8-18-(25) mm long. Capitula sessile, usually solitary but sometimes appearing paired, (3)-4-8 mm diam.; florets numerous; ♀ florets in (4)-5-9 rows. Achenes (1)-1.3-2 mm long, with faces dark brown and pale brown ribs not extending to apex.