15. Sphagnum inundatum Russ., Arch. Naturk Liv-Ehst-Kurlands, ser. 2, Biol. Naturk. 10: 390. 1894; Sphagnum subsecundum Nees ex Sturm var. inundatum (Russ.) C. Jens. Bot. Faeros Dan Invest. 1: 139. 1901.
Sphagnum inundatum var. perfibrosum P. de la Varde, Rev. Bryol. Lichénol. 10: 136. 1938.
Plants rather robust, grayish green or pale brown, in compact cushions. Stem cortex in 1 layer, hyaline cells without fibrils; central cylinder rather thick, yellowish brown. Stem leaves 0.4–0.7 mm × 0.3–0.6 mm, ligulate, rounded obtuse and lacerate at the apex; borders narrow above, clearly widened below; hyaline cells undivided (sometimes divided), often without fibrils and pores, rarely with the traces of fibrils in the upper cells and with scattered pores on the ventral surface. Branches in fascicles of 3–5, with 2–3 spreading. Branch leaves 1.0–1.4 mm × 0.5–0.6 mm, broadly ovate-lanceolate, strongly concave, somewhat secund, gradually narrowed and margins involute at the apex, borders narrowly differentiated; hyaline cells densely fibrillose, with numerous, ringed pores in commissural rows on the dorsal surface, with fewer pores on the ventral surface; green cells in cross section narrowly elliptic or nearly rectangular, centrally located, exposed on both surfaces. Dioicous. Sporophytes not seen.
Chinese specimens examined: HEILONGJIANG: Xiao Xing An Ling (Lesser Khingan Mt.), C. Gao 320 (IFSBH, KUN, MO). JILIN: Jiao-he Co., C. Gao 1499 (IFSBH, KUN), 1514 (IFSBH, KUN, MO). NEI MONGOL: Da Xing An Ling (Greater Khingan Mt.), C. Gao 898, 910 (IFSBH, KUN).
Habitat: in bogs and on humic soil of grasslands or under forests, sometimes submerged in water; Distribution: China, Japan, Europe, and North America.
Illustrations: C. Gao (ed.) 1994 (Pl. 22, figs. 8–10, as Sphagnum subsecundum var. inundatum).