Lycopodium involvens Swartz, Syn. Fil. 182. 1806; Lycopodioides involvens (Swartz) Kuntze; L. pennula Kuntze; Lycopodium caulescens Wallich ex Hooker & Greville; L. microstachyum Desvaux ex Poiret; Selaginella caulescens (Wallich ex Hooker & Greville) Spring; S. caulescens var. belulla Hieronymus; S. caulescens var. brachypoda Baker; S. caulescens var. gracilis W. Bull; S. caulescens var. japonica Baker; S. caulescens var. subintegerrima Spring; S. microstachya (Desvaux ex Poiret) Hieronymus (1913), not Warburg (1900); S. pachystachys Koidzumi; S. pseudostauntoniana Pampanini; S. warburgii Hieronymus.

Plants epilithic or xerophytic, evergreen or seasonally green, erect, 15-35(-65) cm, with creeping subterranean rhizome and stolons; leaves on rhizome and stolons scalelike, pale yellow. Rhizophores restricted to creeping rhizomes and stolons. Main stems branched from middle upward, pinnately branched, stramineous, unbranched main stem 5-25 cm tall, 1-1.5 mm in diam. in lower part, terete, not sulcate, glabrous; primary leafy branches 7-12 pairs, 2 or 3 times pinnately branched, secondary branches 1 or 2 times pinnately branched, tertiary branches forked or once pinnately branched, leafy main stem including leaves 4-6 mm wide at middle, ultimate branches 2-3 mm wide including leaves. Axillary leaves symmetrical, ovate to triangular, 1.1-1.6 × 0.4-1.1 mm, base exauriculate, margin denticulate. Dorsal leaves imbricate, ovate-triangular or ovate-elliptic, 0.6-1.2 × 0.2-0.5 mm, slightly carinate, base cuneate, margin denticulate, apex long acuminate to shortly aristate, parallel to axis. Ventral leaves contiguous or overlapping, slightly ascending, ovate to triangular, 1.4-2.4 × 0.4-1.4 mm, apex subacute or apiculate; basiscopic base rounded, margin entire; acroscopic base enlarged, broader, overlapping stem and branches, margin hyaline, denticulate. Strobili solitary, terminal, compact, tetragonal, 5-15 × 1-1.4 mm; sporophylls uniform, not white-margined, ovate-triangular, sharply carinate, margin denticulate, apex acuminate, without sporophyll-pteryx; megasporophylls and microsporophylls at intervals, or megasporophylls in middle on lower side; microsporangia elliptic, rather thin, cells regular; microspores yellowish orange, megaspores whitish or brown, with equatorial flange.

On rocks in shade or epiphytic on tree trunks in forests; 200-3100 m. Anhui, Chongqing, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Henan, Hubei, Hunan, Jiangxi, Shaanxi, Sichuan, Taiwan, Xizang, Yunnan, Zhejiang [Bhutan, India, Japan, Korea, Laos, Malaysia, Myanmar, Nepal, Philippines, Sri Lanka, Thailand, Vietnam].