25. Sphagnum obtusum Warnst., Bot. Zeitung (Berlin). 35: 478. 1877.
Sphagnum recurvum var. obtusum (Warnst.) Warnst., Hedwigia 23: 121. 1884.
Plants rather large, 8–12 cm high, pale green, tinged with yellowish brown, in loose or compact tufts. Stem cortex in 2–4 layers, hyaline cells large, thin-walled, without fibrils and pores; central cylinder pale yellowish brown, not clearly differentiated from cortical cells. Stem leaves 1.0–1.5 mm long, distantly set, triangular-ligulate, rounded, dentate or sometimes lacerate at the apex; borders narrow above, clearly widened below (ca. 1/3 the leaf base width); hyaline cells broadly rhomboidal, occasionally divided and fibrillose in the upper apex. Branches in fascicles of 4–5, with 2–3 spreading. Branch leaves 2.0–3.0 mm long, ovate-ligulate to lanceolate, undulate when dry, slightly involute near apex; hyaline cells linear-rhomboidal, densely fibrillose, with numerous, small, pore-like membrane thinnings in 1–2 rows on both surfaces; green cells in cross section narrowly isosceles-triangular, exposed on the dorsal surface, enclosed by hyaline cells or sometimes slightly exposed on the ventral surface. Dioicous. Sporophytes not seen.
Chinese specimens examined: HEILONGJIANG: C. Gao 3485(b) (IFSBH); Hong Xing, Vitt 34960 (MO).
Habitat: in open bogs; Distribution: China, Japan, Russian Far East and Siberia, and Europe, and North America.
Illustrations: C. Gao (ed.) 1994 (Pl. 11, figs. 11–14).