43. Sphagnum tenellum Ehrh ex Hoffin., Deutschl. Fl., ed. 2. 22. 1796.
Sphagnum molluscum Bruch, Flora 8: 635. 1825.
Plants slender, rather soft, grayish green or yellowish brown, in loose cushions. Stem cortex in 2–3 layers, hyaline cells large, thin-walled, without fibrils and pores; central cylinder yellowish green. Stem leaves 1.0–1.4 mm × 0.5–0.6 mm, relatively large, oblong-ligulate, rounded-obtuse, often lacerate across the apex; borders narrow above, slightly widened near the base; hyaline cells usually not divided, fibrillose in the upper half or nearly to the base, with pores at the upper and lower corners and with ringed pores at the opposite sides along commissural rows on the dorsal surface, with pores at the opposite corners on the ventral surface. Branches in fascicles of 2–4, with 1–2 spreading. Branch leaves 1.0–1.5 mm × 0.5–0.6 mm, broadly ovate to oblong-ovate, concave, secund when dry, blunt and dentate at the apex; hyaline cells narrowly rhomboidal, densely fibrillose, with pores at the upper and lower corners and with ringed pores at the opposite sides along commissural rows on the dorsal surface, with pores at the opposite corners on the ventral surface; green cells in cross section triangular or trapezoidal, exposed on the dorsal surface, enclosed by hyaline cells or slightly exposed on the ventral surface. Dioicous; antheridial branches yellowish brown. Perigonial leaves similar to vegetative branch leaves in size and shape, yellowish brown. Perichaetial leaves large, concave, dentate at the apex; hyaline cells rarely fibrillose, with pores similar to those of stem leaves. Capsules small. Spores yellowish, smooth, ca. 38 µm in diameter.
Chinese specimens examined: HEILONGJIANG: Da Xing An Ling (Greater Khingan Mt.), C. Gao 12782 (IFSBH, KUN). YUNNAN: Bi-jiang Co., M. Zang 5472 (KUN); Gong-shan Co., Q.-W. Wang 33769, 34107 (PE), M. Zang 485 (KUN, MO), 536, 671 (KUN), A.-L. Zhang 22(d) (KUN), D.-C. Zhang 559 (KUN, MO), 881 (KUN); Yang-bi Co., R.-Z. Fang 81001 (KUN), 81002 (KUN, MO).
Habitat: on wet ground under forests or near streams; also in bogs or on grasslands; Distribution: China, India, Japan, Europe, North America, and North Africa.
This species is similar to Sphagnum cuspidatulum, but it differs in the following features: 1) plants smaller; 2) stem leaves oblong-ligulate; 3) branch leaves broadly ovate to oblong-ovate; and 4) the hyaline cells of branch leaves with pores only at the opposite corners. In contrast, Sphagnum cuspidatulum has the following features: 1) plants larger and stouter; 2) stem leaves triangular; 3) branch leaves ovate-lanceolate; and 4) the hyaline cells of branch leaves with pores at the corners and along commissural rows.
Illustrations: C. Gao (ed.) 1994 (Pl. 23, figs. 1–9).