18. Selaginella hainanensis X. C. Zhang & Nooteboom, Bot. J. Linn. Soc. 148: 323. 2005.
琼海卷柏 qiong hai juan bai
Plants terrestrial, seasonally green, long creeping, 35-80 cm or more. Rhizophores at intervals throughout length of creeping stem and branches, borne on ventral side in axils of branches. Main stems branched throughout, stramineous, 0.4-1 mm in diam. in lower part, subquadrangular, sulcate; primary leafy branches 5-10 pairs, once or twice pinnately branched, secondary branches forked or once pinnately branched, branchlets sparse, adjacent primary branches on main stem 4-9 cm apart; leafy portion of main stem including leaves 6-7 mm wide at middle, ultimate branches 3.4-6 mm wide including leaves. Leaves entire, distinctly white-margined. Axillary leaves on main stems larger than those on branches (often reflexed where rhizophore occurs), broadly ovate or suborbicular, 2.4-3.5 × 1.8-3.6 mm, base attenuate; axillary leaves on branches symmetrical, ovate, broadly elliptic, or oblong-elliptic, 1.9-2.8 × 1-2 mm, base exauriculate, margin entire. Dorsal leaves ± symmetrical, those on main stems obviously larger than those on branches, 3.2-3.8 × 1.6-2 mm, arista 0.4-0.8 mm; dorsal leaves on branches approximate or imbricate, overlapping at leaf apex or often reflexed, ovate, 2-3 × 1-1.8 mm, not carinate, base obtuse, apex long acuminate or aristate, arista 0.5-1 mm. Ventral leaves strongly asymmetrical, those on main stem obviously larger than those on branches, 3.4-4.2 × 2.2-3.2 mm; ventral leaves on branches approximate, spreading, ovate, oblong, or oblong-ovate, 2.5-3 × 1-1.6 mm, apex apiculate; basiscopic base with 1 or few cilia, margin entire; acroscopic base enlarged, broader, overlapping stem and branches, margin entire. Strobili solitary, terminal, compact, tetragonal, 7-25 × 4-5 mm; sporophylls uniform, ovate-lanceolate, carinate, margin entire, apex long acuminate to aristate; megasporophylls in basal portion on lower side of strobilus or megasporophylls in middle on lower side; microsporangia transversely elliptic, relatively thick, marginal cells differentiated, smaller with thin walls; microspores pale yellow, megaspores white-yellow or whitish (or sometimes with dark central part), reticulate.
● Forests of rubber trees, forming mats on ground; below 100 m. E Hainan.
Selaginella hainanensis is endemic to the coastal region of E Hainan.