5. Sphagnum compactum P. de Cand. ex Lam. & P. de Cand., Fl. Franc., ed. 2. 2: 443. 1805.
Sphagnum compactum var. imbricatum Warnst., Bot. Gaz. 15: 226. 1890.
Plants stout in dense or compact tufts, grayish to yellowish green or tinged with pinkish red. Stem cortex in 2–3 layers, hyaline cells large, thin-walled, without fibrils, with a single pore; central cylinder yellowish brown. Stem leaves 0.50–0.55 mm × 0.6 mm, triangular-ligulate, with rounded, involute, often lacerate apices; borders clearly widened at leaf base, occupying about 1/6 leaf width; hyaline cells rhomboidal, not divided, without fibrils, with pores only on the ventral surface. Branches short, stout, and crowded in fascicles of 4–6 with 2–3 spreading. Branch leaves 1.6–2.6 mm × 0.8–1.6 mm, broadly ovate, several times larger than stem leaves, concave with involute-concave apex; borders indistinct, sometimes denticulate along margins; hyaline cells densely fibrillose, with numerous pseudopores, 2–3 pores at the corners of each cell on the ventral surface, few to numerous rather larger pores at the ends on the dorsal surface; green cells in cross section small, narrowly oval to elliptic, centrally located or slightly widened toward the dorsal surface, enclosed by hyaline cells on both surfaces. Monoicous. Perigonial leaves not differentiated. Perichaetial leaves broadly ovate to oblong ovate, subsecund, concave. Spores yellowish brown, 32–35 µm in diameter.
Chinese specimens examined: HEILONGJIANG: C. Gao 937 (IFSBH, KUN). XIZANG: Ri-dong Co., M. Zang 5207 (KUN, MO). YUNNAN: Gong-shan Co., M. Zang 496 (KUN, MO), Q.-W. Wang 33706 (KUN, PE); between Nu-jiang (river) and Yiluowadijiang (river), Handel-Mazzetti 9539 (KUN); Du-long-jiang (river), Q.-W. Wang 33874, 34143 (PE), M. Zang 545 (KUN, MO), 912 (KUN).
Habitat: on moist ground under forests or on rocks with dripping water in high mountains; Distribution: China, Southeast Asia, Russian Far East, Europe, North America, North Africa, and Australia.
This species is characterized by having very crowded, stout and blunt branches, very small stem leaves that are about 1/8 – 1/6 of the length of branch leaves, and by the green cells of branch leaves centrally located.
Illustrations: C. Gao (ed.) 1994 (Pl. 3, figs. 1–9).