3. Sphagnum aongstroemii C. Hartman., Handb. Skand. Fl., ed. 7. 399. 1858.
Plants medium-sized, brownish green to yellowish brown tinged with blue, in dense tufts. Stem cortex in 3–5 layers, hyaline cells thin-walled, without fibrils; central cylinder yellowish brown. Stem leaves 1.0–1.4 mm × 0.6–0.8 mm, ligulate, flat, broader at base, narrowed from the middle of leaves, rounded and slightly lacerate at the apex; borders differentiated, narrow above the middle, clearly widened below the middle, ca. 1/3 leaf width at base; hyaline cells divided in the upper parts of leaves, without fibrils and pores. Branches in fascicles of 3–5. Branch leaves ca. 1.5 mm × 1.0 mm, imbricate, loosely arranged, broadly ovate with broad, blunt and dentate apex, margins slightly involute; borders consisting of 1–3 rows of linear cells; hyaline cells linear-rhomboidal, with small, short-elliptic, ringed pores at the ends and at corners on the dorsal surface, pores enlarged near the leaf base; with a few medium-sized ringed pores in cell ends in the upper parts of leaves on the ventral surface, few to none near the base; green cells in cross section elliptic, centrally located, equally exposed on both surfaces. Dioicous. Spores deep brownish, papillose.
Chinese specimens examined: NEI MONGOL: Da Xing An Ling (Greater Khingan Mt.), P.-C. Chen et al. 932 (IFSBH, KUN, PE), 998 (IFSBH, KUN, MO).
Habitat: on ground under coniferous forests or wet grasslands in high mountains; Distribution: China, Russian Far East and Siberia, Europe, and North America.
Illustrations: C. Gao (ed.) 1994 (Pl. 1, figs. 8–14).