31. Sphagnum platyphyllum (Lindb. ex Braithw.) Sull. ex Warnst., Flora. 67: 481. 1884; Sphagnum laricinum var. playtphyllum Lindb., Not. Sällsk. Fauna Fl. Fenn. 13: 403. 1874, nom. inval. Lindb. ex Braithw., Monthly Microscope. J. 13: 230. 1875.
Sphagnum subsecundum var. platyphyllum (Braithw.) Card., Bull. Soc. Bot. Belg. 25(1): 73. 1886. Sphagnum subsecundum ssp. playtphyllum (Braithw.) Herib., Mém. Acad. Sci. Clermont-Ferrand, sér. 2, 14: 454. 1899. Sphagnum contortum var. platyphyllum (Braithw.) Åberg, Ark. Bot. 29A(1): 34. 1937. Sphagnum isophyllum Russ., Arch. Naturk. Liv-Ehst-Kurlands, Ser. 2, Biol. Naturk., 10: 415. 1894.
Plants rather stout and robust, grayish green, tinged with brownish color, in loose tufts. Stem cortex in 1–3 layers, hyaline cells large, thin-walled, without fibrils, mostly porose; central cylinder yellowish brown. Stem leaves 1.0–1.8 mm × 0.8–1.0 mm, broadly ligulate to elliptic, concave, margins involute, borders differentiated; hyaline cells rarely divided, fibrillose, or sometimes indistinct, with a few small, ringed pores at the ends and corners on both surfaces. Branches in fascicles of 3–5, with 2–3 spreading. Branch leaves 1.5–2.2 mm × 0.8–1.2 mm, broadly ovate to elliptic, strongly concave, margins involute, borders narrowly differentiated, obtuse and denticulate at the apex; hyaline cells with a few, small pores at the corners on the ventral surface, with more ringed pores, often scattered at margins along commissural rows on the dorsal surface; green cells in cross section elliptic, centrally located, exposed equally on both surfaces. Dioicous. Sporophytes not seen.
Chinese specimens examined: HEILONGJIANG: Xiao Xing An Ling (Lesser Khingan Mt.), Collector unknown (IFSBH, MO). NEI MONGOL: Da Xing An Ling (Greater Khingan Mt.), P.-C. Chen & C. Gao 810 , 832 (IFSBH, KUN, MO), P.-C. Chen & C. Gao 829, 830 (IFSBH, MO).
Habitat: in bogs and wetlands near streams; Distribution: China, Japan, Russian Far East and Siberia, Europe, Greenland, and North America.
Illustrations: C. Gao (ed.) 1994 (Pl. 22, figs. 11–12).