Selaginella flagellifera W. Bull; S. hirticaulis Warburg; S. utchinensis Koidzumi.

Plants terrestrial or epilithic, evergreen, erect or creeping, 15-45 cm, with creeping subterranean rhizome and stolons. Rhizophores restricted to creeping rhizomes and stolons. Main stems branched in upper part, pinnately branched, stramineous, stem 1-1.5 mm in diam. at lower part, angulate or subquadrangular, sulcate, unbranched main stem glabrous or pubescent in leafy branched part, apex of main creeping stems flagelliform; primary leafy branches 4-7 pairs, 2 times pinnately branched, leafy branches dorsiventrally flattened, pubescent on ventral side, leafy portion of main stem including leaves 4-5 mm wide at middle, ultimate branches 2-3 mm wide including leaves. Axillary leaves on branches slightly asymmetrical, ovate-lanceolate or elliptic, 1.8-2.4 × 0.8-1.2 mm, base exauriculate, margin ciliolate at base. Dorsal leaves on branches contiguous, ovate, 0.8-1.4 × 0.6-0.8 mm, not carinate, base obliquely cordate, margin very ciliolate, apex aristate. Ventral leaves on branches contiguous or imbricate, slightly ascending, oblong-falcate or falcate, 1.8-3.2 × 1.2-1.6 mm, apex acute; basiscopic base rounded, margin subentire except base with a few cilia; acroscopic base not enlarged, not overlapping stem and branches, margin ciliolate to denticulate. Strobili solitary, terminal, compact, tetragonal, 5-15 × 1.5-2 mm; sporophylls uniform, not white-margined, ovate, sharply carinate, margin denticulate or ciliolate, apex acuminate; megasporophylls in basal portion on lower side of strobili, or megasporophylls and microsporophylls at intervals, microsporangia elliptic; microspores yellowish orange, megaspores pale yellow, whitish, or dark brown, without equatorial flange, undulate-rugose.

Plants of Selaginella biformis are usually of two forms: main stems erect or creeping, creeping plants usually glabrous or less hairy. Branches are also flagelliform, forming new plants. Dahlen (Bot. J. Linn. Soc. 98: 277-302. 1988) reported that of 53 strobili of S. biformis with megasporangia, only five had mature or senescent megasporangia while the rest had only immature sporangia.

Shaded places or on rocks in forests; 100-1500 m. Guangdong, Guangxi, Guizhou, Hainan, Yunnan [India, Indonesia, Japan, Laos, Malaysia, Myanmar, Philippines, Sri Lanka, Thailand, Vietnam].