Plants small to moderately robust, green to yellow green, with a brownish tinge in hummocks; forms mats and cushions. Stems yellowish green with some brown bands; 2-3 layers of superficial cells. Stem leaves shorter than branch leaves, 0.8-1.6 mm, lingulate, hyaline cells non-septate above and commonly 1-septate below. Branches short and blunt, branch leaves imbricate. Branch fascicles typically with 2 spreading and 2 hanging branches. Branch stems with single layer of cortical cells. Branch leaves 0.9-2 mm, ovate, with conspicuously truncate apex, hyaline cells bulging on both surfaces, with 1-4 large circular to elliptic pores per cell on convex surface and 4-7 elliptic pores per cell on concave surface, internal commissural walls faintly papillose, cholrophyll cells elliptical to elliptical-ovate withn the broadest part typically some distance from convex surface. Sexual condition unknown.

Forms mats and cushions in weakly minerotrophic arctic mires; low elevations; Yukon; Alaska; Europe.

Sphagnum tundrae can be separated from other species in sect. Squarrosa most readily by its truncate branch leaves.