白边卷柏 bai bian juan bai

Lycopodioides albocincta (Ching) H. S. Kung; Selaginella albidocincta Ching.

Plants terrestrial or epilithic, xerophytic, seasonally green, erect or long creeping; fertile stems erect, 15-30 cm or more. Rhizophores restricted to base of erect stems or at intervals throughout length of creeping stem and branches, borne on ventral side in axils of branches. Main stems branched throughout or from near base or from lower part upward, pinnately branched, stramineous or brown, 0.5-1 mm in diam. at lower part, stem terete, not sulcate, glabrous, basal lateral branches sometimes developed into rather long branch systems; primary leafy branches 5-8 pairs, 2 or 3 times forked, branchlets sparse, adjacent primary branches on main stem 3-5 cm apart, main stem including leaves 0.5-1 mm wide at middle, ultimate branches 0.5-1.6 mm wide including leaves. Leaves alternate, inconspicuously dimorphic, leathery, shiny, white-margined, veins forked. Axillary leaves on branches symmetrical, oblong, 0.6-1.8 × 0.2-0.5 mm, base exauriculate, margin ciliolate. Dorsal leaves ± symmetrical, those on main stems not obviously larger than those on branches; dorsal leaves on branches elliptic, 0.8-1.4 × 0.4-0.7 mm, contiguous or imbricate, strongly embracing stem and covering ventral leaves, apex mucronate. Ventral leaves asymmetrical, those on main stem not obviously larger than those on branches; ventral leaves on branches slightly ascending, elliptic, 0.8-1.5 × 0.2-0.6 mm, apex mucronate; basiscopic base rounded, margin entire (or minutely denticulate), involute; acroscopic margin minutely ciliolate or denticulate. Strobili solitary, terminal, compact, tetragonal, 4-8 × 1.2-1.8 mm; sporophylls unlike sterile leaves, monomorphic, broadly white-margined, broadly ovate, margin ciliolate, apex acute; strobili with only 1 megasporophyll at base of lower side, elsewhere with microsporophylls; microsporangia orbicular, rather thin, cells uniform; microspores orange-red, megaspores brown.

● Rocky slopes in dry warm valleys, under shrubs; 1700-3300 m. Sichuan, Xizang, Yunnan.

Selaginella albocincta is endemic to China, and its habit is very close to the Indian S. adunca A. Braun ex Hieronymus. They both exhibit forked veins, which might be an adaptation to their dry habitats.