Sphagnum sect. Sphagnum

Plants typically large, with distinct capitulum; green, pale green, yellowish, red, tan, brown to dark brown. Stems green, brown or reddish, outer cortex of 3–4 layers of inflated, thin-walled cells, superficial cells with conspicuous to faint spiral fibrils, no or strong ornamention on interior wall, and 1–6 round to ovate pores per cell. Stem leaves typically as large as or larger than branch leaves, lingulate to ovate-lingulate with broad rounded apex, border fringed; hyaline cells rhomboid, efibrillose or fibrillose, sometimes ornamented, aporose, 0–2-septate, and often resorbed on exterior surface. Branches dimorphic, spreading branches tumid, pendent branches usually shorter and more slender. Branch fascicles with 2–3 spreading branches and 1–3 pendent branches. Branch stems green, surrounded by 1 layer of enlarged thin-walled cells, typically porose and fibrillose, in some species ornamented on interior wall; retort cells absent. Branch leaves ovate to broadly ovate, apex cucullate and roughened on convex surface; margin toothed; hyaline cells fibrillose; convex surface pores round to elliptic, usually with 1 at each corner of three adjacent hyaline cells; chlorophyllous cells lenticular to triangular, sometimes with wall ornamentation visible in transverse section; chlorophyllous cells enclosed, equally exposed, or more broadly exposed on concave surface, end walls thickened or unthickened. Sexual condition usually dioicous. Capsule 2 mm or more. Spores typically 22–30 µm, distal surface sculpture may be present; proximal laesura usually more than 0.5 spore radius.

Distribution

Worldwide except Antarctica.

Discussion

Species 54 (12 in the flora).

Selected References

None.

Lower Taxa

Sphagnum affine, Sphagnum alaskense, Sphagnum austinii, Sphagnum centrale, Sphagnum henryense, Sphagnum imbricatum, Sphagnum magellanicum, Sphagnum palustre, Sphagnum papillosum, Sphagnum perichaetiale, Sphagnum portoricense, Sphagnum steerei

Key

1	Branch leaf chlorophyllous cells in transverse section ± equilateral-triangular, often with conspicuous vertically oriented comb-fibrils on the hyaline cells where overlying chlorophyllous cells	> 2
1	Branch leaf chlorophyllous cells in transverse section narrowly triangular, trapezoidal, truncate-elliptic, elliptic or lenticular; comb-fibrils if present horizontally oriented	> 6
2	Branch cortical cells with funnel-like projections often extending halfway or more into the next cell; branches strongly clavate and blunt.	Sphagnum portoricense
2	Branch cortical cells with flat end walls or with weak funnel-like projections extending less than halfway into the next cell; branches not clavate or if clavate, with pointed ends	> 3
3	Interior layer of stem cortical cells with distinct comb-lamellae; branch leaves with or without comb-lamellae; stem leaves without comb-lamellae.	Sphagnum affine
3	Interior layer of stem cortical cells without comb-lamellae or at least not visible with a light microscope; branch leaves with comb-lamellae; stem leaves with or without comb-lamellae	> 4
4	Stem leaf hyaline cells with distinct comb-lamellae; branches clavate and pointed; branches leaves strongly imbricate.	Sphagnum austinii
4	Stem leaf hyaline cells without distinct comb-lamellae; branches not clavate; branch leaves more or less spreading	> 5
5	Stem leaves short (ca. 0.8-1.1 mm); branch leaves broad (breadth:length ca. 0.7-0.8), branch leaf comb-lamellae usually distinct only in lower half of leaf; branch cortical comb-lamellae present; plants yellow to golden brown.	Sphagnum imbricatum
5	Stem leaves long (ca. 1.1-1.5 mm.); branch leaves narrow (breadth:length ca. 0.6-0.68), branch leaf comb-lamellae distinct throughout most of leaf; branch cortical cell comb-lamellae usually absent; plants dark brown.	Sphagnum steerei
6	Branch leaf chlorophyllous cells in transverse section short-elliptic, elliptic to lenticular, and enclosed on both surfaces	> 7
6	Branch leaf chlorophyllous cells in transverse section narrowly triangular, rectangular to truncate-elliptic, exposed equally on both surfaces or more broadly on the convex surface	> 9
7	Branch leaf chlorophyllous cells in transverse section short-elliptic and well enclosed; plants purplish red when pigmented.	Sphagnum magellanicum
7	Branch leaf chlorophyllous cells in transverse section narrowly elliptic and slightly enclosed on both surfaces; plants brown when pigmented	> 8
8	Branch leaf chlorphyllous cells in transverse section without thickened ends walls; superficial stem cortical cells with reinforcing fibrils weak or absent; branch leaf hyaline cells where overlying chlorophyll cells often with comb-fibrils	Sphagnum alaskense
8	Branch leaf chlorphyllous cells in transverse section with thickened end walls; superficial stem cortical cells with strong reinforcing fibrils; branch leaf hyaline cells where overlying chlorophyllous cells smooth.	Sphagnum centrale
9	Branch leaf hyaline cells papillose where overlying chlorophyllous cells.	Sphagnum papillosum
9	Branch leaf hyaline cells epapillose where overlying chlorophyllous cells	> 10
10	Superficial stem cortical cells with fibrils weak or lacking; chlorophyllous cells rectangular to truncate-elliptic, exposed equally on both surfaces.	Sphagnum perichaetiale
10	Superficial stem cortical cells with strong fibrils; chlorophyllous cells triangular, exposed more broadly on concave surface	> 11
11	Branch leaf hyaline cells where overlying chlorophyllous cells often with irregular worm-like ridges, especially at the leaf base; pores on the convex surface numerous, small and round to elliptic.	Sphagnum henryense
11	Branch leaf hyaline cells smooth throughout; pores on the convex surface elliptic to flattened-elliptic, not numerous.	Sphagnum palustre