Perennials, 2-40(-70) cm (taproots, sometimes thickly rhizomatous, sometimes with branching caudices). Stems decumbent-ascending to erect, simple (essentially scapose), usually distally finely, loosely tomentose, sometimes stipitate-glandular. Leaves mostly basal (persistent rosettes), cauline reduced; alternate; sessile; blades 3-nerved, linear to oblanceolate, margins entire (apices acute to obtuse or rounded ), faces glabrous, sparsely villous, or stipitate-glandular. Heads radiate, borne singly. Involucres broadly turbinate, (5-12 ×) 10-20 mm. Phyllaries 25-40 in (2-)3-4 series, appressed (commonly purplish), 1(-3)-nerved (thin, not resinous; often low-keeled), linear to linear-elliptic or oblanceolate, subequal, usually herbaceous, sometimes proximal margins indurate, faces finely and loosely tomentose. Receptacles flat, shallowly pitted, epaleate. Ray florets 10-40, pistillate, fertile; corollas white, often drying blue to purple. Disc florets 30-55, bisexual, fertile; corollas yellowish at maturity, tubes shorter than tubular throats (barely constricted), lobes 5, erect, lanceolate to deltate; style-branch appendages linear-lanceolate. Cypselae (brownish) narrowly cylindric, ribs 5-10 (raised), faces glabrous or sparsely strigillose; pappi persistent, of 25-40, tawny-white, barbellate, apically attenuate bristles in 1 series, sometimes plus shorter bristles or setae in a second, outer series. x = 9.

Oreostemma is distinguished by its basal rosettes of narrow, 3-nerved leaves, single heads on scapose stems, turbinate involucres with (2-)3-4 subequal series of herbaceous phyllaries, white rays, long style-branch appendages, and cylindric cypselae. The species mostly have been previously treated within Aster.