Description from Flora of China
Lycopodium helveticum Linnaeus, Sp. Pl. 2: 1104. 1753; Bernhardia helvetica (Linnaeus) Gray; Diplostachyum helveticum (Linnaeus) P. Beauvois; Heterophyllium helveticum (Linnaeus) Hieronymus; Lycopodioides helvetica (Linnaeus) Kuntze; L. jiulongensis H. S. Kung, Li Bing Zhang & X. S. Guo; L. mariesii (Baker) Kuntze; Lycopodium radicans Schrank; Selaginella mariesii Baker; Stachygynandrum helveticum (Linnaeus) P. Beauvois ex J. Saint-Hilaire.
Plants terrestrial or epilithic, seasonally green, shortly creeping; fertile stems erect, 5-15 cm. Rhizophores at intervals throughout length of creeping stem and branches, borne on ventral side in axils of branches. Main stems branched throughout, stramineous, 0.2-0.4 mm in diam. in lower part, stem angulate, sulcate; primary leafy branches 2-5 pairs, simple, forked, or once pinnately branched, branchlets sparse, adjacent primary branches on main stem 2-3 cm apart, leafy branches and main stems glabrous, dorsiventrally flattened, leafy portion of main stem including leaves 3-3.8 mm wide at middle, ultimate branches 2-3.6 mm wide including leaves. Axillary leaves on branches ± symmetrical, ovate-lanceolate or elliptic, 1.4-1.6 × 0.4-0.8 mm, base exauriculate, margin ciliolate. Dorsal leaves ± symmetrical, those on main stems not obviously larger than those on branches; dorsal leaves on branches contiguous or imbricate, ovate or ovate-lanceolate, 1.2-1.6 × 0.5-0.8 mm, base obtuse, margin ciliolate, apex long acuminate or aristate, often reflexed. Ventral leaves asymmetrical, those on main stem not obviously larger than those on branches; ventral leaves on branches spreading or slightly deflexed, oblong-ovate or broadly ovate, 1.6-2 × 0.8-1.2 mm, apex acute or aristate, often bent upward; basiscopic margin ciliolate; acroscopic base enlarged, broader, overlapping stem and branches, margin ciliolate. Fertile branches erect, 3-6 cm including strobili. Strobili solitary or forked, terminal, lax, or lax in lower portion and compact in upper part, cylindric, 12-35 × 2-4 mm; sporophylls unlike sterile leaves or similar, uniform, not white-margined, margin ciliolate, apex long acuminate; megasporophylls in basal portion on lower side of strobilus or megasporophylls and microsporophylls at intervals; microsporangia elliptic or suborbicular, relatively thick, with relatively large cells at central part; microspores orange-red, megaspores orange or yellowish orange.
On wet moss-covered cliffs, in rock crevices, usually on damp shaded banks in mixed forests, among moss; (200-)2600-3200(-3800) m. S Gansu, Hebei, Heilongjiang, Jilin, Liaoning, Nei Mongol, Qinghai, Shaanxi, Shandong, Sichuan, Xizang, Yunnan [N India, Japan, Korea, Mongolia, Nepal, Russia; Europe].