Deschampsia nubigena is a tufted perennial grass with stiff, glabrous culms that grow 30-100 cm tall. The leaves are simple and alternate, with 5-30 cm long blades and 0.5-1.5 mm wide, folded, and glabrous surfaces. The margins of the leaves are scabrous, and they have parallel veins. The sheaths are also glabrous, and the ligule is membranous, lanceolate-acuminate, measuring 5-8 mm long. The inflorescences are paniculate, 5-30 cm long, usually open, and oblong-ovate. The capillary branches in the inflorescences are in fascicles, with some being naked at the base and others bearing spikelets near the base. The spikelets are 2-flowered, 4.5-5.5 mm long, glabrous, with a pubescent rachilla that is prolonged beyond the second floret. The first glume is about 3.5 mm long, and the second glume is around 4 mm long with a scabrous keel. The lemmas are thin, hyaline, and scabrous, approximately 4 mm long. They have a deeply 4-toothed apex and an awn that is 6-9 mm long, usually bent near the lower third. The callus hairs are about 1 mm long. The palea has serrulate keels and is bifid. The fruit is a caryopsis, ovoid, cylindrical about 1.6 mm long, with a rostellate apex and a slightly rugose surface. It is found in various habitats, including mesic to wet forests, bogs, subalpine shrubland, cinder fields, and alpine grasslands, with an elevation range of 30-2,830 meters.