28. Sphagnum papillosum Lindb., Acta Soc. Sci. Fenn. 10: 280. 1872.
Plants rather robust, pale green or yellow to brown, in dense compact carpets. Stem cortex in 3–4 layers, hyaline cells thin-walled, fibrillose, each cell with 1–3, rarely 5, rather small pores; central cylinder brown or blackish. Stem leaves 0.7–0.9 mm × 0.6–0.7 mm, short-ligulate to oblong-ligulate, hyaline and finely fringed at the rounded apex; hyaline cells mostly 1-divided, without fibrils, largely resorbed in the upper half on both surfaces, with some development of membrane pleats in the lower half. Branches stout, in fascicles of 4–5, with 2 spreading. Branch leaves 0.7–1.0 mm × 0.7–0.8 mm, imbricate or slightly spreading, broadly ovate, cucullate-concave and dorsally roughened at the apex, denticulate along a marginal resorption furrow; hyaline cells rhomboidal, with 4–10 rounded or elliptic, ringed pores in the corners and along commissural rows on the dorsal surface, with rather small, ringed pores in the cell angles and in the upper and lateral portions with 1–5 large, rounded median pores on the ventral surface; green cells in cross section narrowly trapezoidal or sometimes nearly triangular to truncate elliptic, exposed more broadly on the ventral surface, the inner walls of adjacent hyaline cells densely papillose. Dioicous. Sporophytes not seen.
Chinese specimens examined: HEILONGJIANG: Da Xing An Ling (Greater Khingan Mt.), C. Gao 12745 (IFSBH, MO). JILIN: Changbai Shan (Mt.),Yuan-chi, C. Gao 22166 (IFSBH, MO). NEI MONGOL: Da Xing An Ling (Greater Khingan Mt.), H.-F. Xie 00071 (IFSBH, MO).
Habitat: in open swamps; Distribution: China, Japan, Europe, Greenland, and North America.
Illustrations: Crum 1984 (Fig. 6, a–n).