Plants perennial, cespitose from decumbent bases. Taproots filiform; basal offshoots present. Stems erect or ascending, green, (8-)10-15(-20) cm, glabrous, internodes of flowering stems 0.8-1.2 times as long as leaves. Leaves overlapping proximally, variably spaced distally, connate proximally, with ± loose, scarious sheath 0.1-0.2 mm; blade spreading or ascending to outwardly curved, green, flat, 1-veined, linear-oblanceolate to linear-spatulate, (10-)20-30(-40) × 1-3 mm, flexuous, margins not thickened, minutely scarious, smooth, apex green, obtuse to broadly acute, shiny, glabrous, axillary leaves absent. Inflorescences flowers solitary, terminal, or 1-3-flowered cymes; bracts narrowly lanceolate, herbaceous. Pedicels 12-30 cm, glabrous. Flowers: hypanthium dish-shaped; sepals very weakly 3-veined, broadly oblong (herbaceous portion broadly oblong), 2-3 mm, not enlarging in fruit, apex green, obtuse or rounded, not hooded, glabrous; petals oblong or obovate, 1.6-2 times as long as sepals, apex rounded to truncate, entire or slightly emarginate. Capsules broadly ovoid, (2-)3-3.5 mm, equaling or longer than sepals. Seeds reddish brown, asymmetrically reniform with radicle prolonged into beak, not compressed, 0.5-0.7 mm, reticulate. 2n = 20. Flowering summer. Shaded sand-rock ledges and bluffs; of conservation concern; 400-600 m; Ky., Tenn. Minuartia cumberlandensis may be most closely related to M. groenlandica and M. glabra; R. Kral (1983) noted that it may be distinguished from either of those taxa by leaf size and shape, seed sculpture, phenology, and habitat preference (shaded sandstone versus sunny granitic flat-rocks).
Minuartia cumberlandensis is in the Center for Plant Conservation's National Collection of Endangered Plants.