Sphagnum imbricatum Hornschuch ex Russow 1865

K. I. Flatberg (1984) considered Sphagnum imbricatum to be East Asian in distribution but a recent collection in Selawik National Wildlife Refuge places it in the North American flora. It will undoubtedly be found elsewhere. Sphagnum imbricatum is closest in morphological detail to S. steerei, but the latter is a very dark colored and densely branched species whereas S. imbricatum is quite light in color and not particularly dense.

Plants 7–15 cm high, green to yellowish green or yellowish brown, in loose or extensive, compact cushions. Stem cortex in 3–5 layers, hyaline cells large and thin-walled, with fibrils and pores; central cylinder yellowish brown. Stem leaves 1.0–1.8 mm × 0.8–1.0 mm, short, broadly ligulate, slightly narrowed at base, flat in the upper part, lacerate at the rounded apex; hyaline cells generally divided, without fibrils, or rarely with indistinct fibrils. Branches in fascicles of 4–5, with 2 spreading. Branch leaves 1.5–2.5 mm long, imbricate, concave, broadly ovate to rounded ovate, cucullate-concave near the apex, hyaline and slightly dentate at the apex, marginal border indistinct; hyaline cells densely fibrillose, with numerous commissural pores on the dorsal surface, with pores at the upper cell angles becoming larger and fewer near the bases on the ventral surface, the inner walls adjacent to green cells often dense with fringe-fibrils; green cells in cross section isosceles-triangular, exposed on both surfaces, more broadly so on the ventral surface. Dioicous; antheridial branches reddish brown. Perigonial leaves large, ovate; perichaetia growing at base of capitulum branches. Spores yellowish brown, smooth.

Plants moderate-sized, weak-stemmed, lax; yellowish to golden brown; forming loose carpets; branches loosely imbricate. Stems yellow to brown, superficial cortical layer with spiral reinforcing fibrils visible, 1 or more pores/cell, comb-fibrils on interior wall. Stem leaves short-rectangular, 0.8-1.1 mm, hyaline cells mostly non-septate and absent comb-fibrils. Branch fascicles with 2 spreading and 1-2 hanging branches. Branch stems with hyaline cells non-ornamented, no or weak funnel-like projections on the end walls of cortical cells, cortical cell walls usually with large round pores. Branch leaves ovate to ovate-elliptic, 1.4-1.8 mm; hyaline cells on convex surface with numerous pores along the commissures; comb-lamellae obvious only in proximal ¹/2 of leaf; chlorophyllous cells broadly triangular in transverse section and well-enclosed on the convex surface. Sexual condition dioecious. Spores (22) 24-27(-28) µm, surface granulate.

Distribution: China, India, Korea, Japan, Caucasus, Russia, Europe, North, Central, and South America.

Habitat: in bogs or wet humic soil under coniferous forests.

Sphagnum imbricatum Hornsch.; Russow, Beitr Torfm. 21. 1865. Sphagnum Austini Sull.; Aust. Musci App. 3. 1870.
Plants low and compact to fairly robust, green or more or less tinged with brown. Woodcylinder brown; cortical cells of the stem in 3-4 layers, their walls thin, reinforced by fibrilbands, the outer cells irregularly quadrilateral to pentagonal, generally longer than wide, each with 4-S or even 10 irregularly rounded pores: stem-leaves of fair size, Ungulate to slightly spatulate, the hyaline border less wide and conspicuous than in the next species, the hyaline cells sometimes divided, near the apex of the leaf about as wide as long, narrower below, their membrane on the inner surface without pores or fibril-bands, on the outer surface entirely resorbed: branches normally in fascicles of 5, 2 spreading, their cortical cells in a single layer, best developed in the lower and middle portion of the branch, with the basal wall plane or nearly so; cell-walls reinforced inwardly by numerous fibril-bands, the outer wall sometimes showing a single pore or rarely also a second one; cortical cells of both stem and branches showing on that part of their inner surface immediately overlying the wood-cylinder a corrugation consisting of alternating ridges and grooves which continue the direction of the fibrilbands but the ridges are lower and broader in section and much more numerous than the bands: leaves of spreading branches imbricate or sometimes squarrose-spreading, ovate, not bordered , but denticulate along the margin ; hyaline cells fibrillose throughout, 4-6 times as long as wide except in the cucuUate apex where they are shorter, on the inner surface with few small ringed pores in the comers of the cells in the apical part of the leaf and also very large roimded pores, 2-12 in each cell, their diameter often nearly equal to the width of the cell, arranged in a single row except toward the sides of the leaf where the row is sometimes double, in rare cases these pores reduced or lacking, on the outer surface with very numerous elliptic pores along the commissures, 4-12 in each cell except in short cells of the cucullate apex where the membrane is largely resorbed forming a single large opening in each cell: chlorophyl-cells exposed on the inner siu-face, equilateral-triangular in section; hyaline cells very convex on the outer surface, up to one half of the diameter of the cell; inner walls of hyaline cells where overling chlorophyl-cells beset with fringe-fibrils, J. e., approximately parallel, somewhat irregularly running ridges, which may be lacking in the upper part of the leaf; resorption-furrow present. Dioicous. Antheridial branches and leaves hardly differentiated except as the latter are slightly more pigmented (brown). Fruiting branches erect; perichaetial leaves large, ovate, with a hyahne toothed border especially toward the apex, the outer cells next the border of two sorts as in normal leaf-structure, the hyaline ones fibrillose and porose, the cells of the remaining inner portion of the leaf uniform, narrow, without fibrils or pores: capsule globose, brown: spores brown-yellow, 20-25 m in diameter, smooth.
Type locality: Kamchatka.
Distribution ; Newfoundlandand southward near the coast to Georgia, Alabama, and Mississippi; Indiana; Alaska; Cuba; also in Europe and Asia.

Sphagnum imbricatum is a species of moss in the family Sphagnaceae, native to cool temperate parts of Europe and eastern North America, and found sporadically elsewhere. In the past it was used as a substitute for cotton in surgical dressings.