Selaginella mongholica Ruprecht var. rossii Baker, J. Bot. (Hooker) 21: 45. 1883; Lycopodioides rossii (Baker) Tzvelev.

Plants epilithic, xerophytic, seasonally green, creeping, 10-25 cm or more. Rhizophores at intervals throughout length of main stem, on dorsal side in axils of stem branches. Main stems branched throughout, reddish, ca. 0.2 mm in diam. in lower part, terete, not sulcate, glabrous; primary leafy branches 3-10 pairs, once or twice forked, secondary branches forked, branchlets sparse, adjacent primary branches on main stem 2-3 cm apart, leafy portion of main stem including leaves 4-4.5 mm wide at middle, ultimate branches 3-4 mm wide including leaves. Axillary leaves on main stems larger than those on branches, ovate, base not peltate, attenuate; axillary leaves on branches symmetrical, elliptic, narrowly elliptic, or oblong, 1.6-2 × 1-1.2 mm, base exauriculate, margin lacerate-ciliolate (in middle, subentire to base and to apex). Dorsal leaves asymmetrical, those on main stems not obviously larger than those on branches; dorsal leaves on branches contiguous or imbricate, ovate-elliptic or rhomboid-ovate, 1.4-1.6 × 0.8-1.1 mm, carinate, base attenuate, peltate, margin sparsely and shortly lacerate-ciliolate, apex acuminate or cuspidate. Ventral leaves asymmetrical, those on main stem not obviously larger than those on branches; ventral leaves on branches as distant as width of leaf, usually deflexed, oblong or oblong-obovate, 1.8-2.1 × 0.9-1.2 mm, apex acuminate; basiscopic margin subentire, involute; acroscopic base rounded, overlapping stem and branches, margin lacerate-ciliolate (in basal half). Strobili solitary, terminal, compact, tetragonal, 5-15 × 1-1.5 mm; sporophylls uniform, not white-margined, ovate-triangular, sharply carinate, margin sparsely ciliolate, apex acute; megasporophylls in basal portion on lower side of strobilus; microsporangia reniform, relatively thick; microspores yellowish orange or pale yellow, rugose, megaspores whitish, irregularly papillate.

In rock crevices, on rocks in forests, on shaded rocks; 200-800 m. Heilongjiang, Jilin, Liaoning, Shandong [Korea, Russia (Far East)].