Sphagnum sect. Sphagnum in Bryophyte Flora of North America @ efloras.org

1a. Sphagnum sect. Sphagnum Linnaeus, Species Plant. 1753.

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 rhomboidal, efibrillose, 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 onthickened. Sexual condition usually dioicous. Capsules 2 mm or more. Spores typically 22--30 µm, distal surface sculpture may be present; proximal laesura usually more than 0.5 spore radius.

1 Branch leaf chlorophyllous cells in transverse section more or less equilateral-triangular, often with conspicuous vertically oriented comb-fibrils on the hyaline cells where overlying chlorophyllous cells. (2)

+ Branch leaf chlorophyllous cells in transverse section narrowly triangular, trapezoidal, truncate-elliptic, elliptic or lenticular; comb-fibrils if present horizontally oriented. (5)

2 (1) Branch cortical cells with funnel-like projections often extending halfway or more into the next cell; branches strongly clavate and blunt. Sphagnum portoricense

+ 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 (2) Interior layer of stem cortical cells with distinct comb-lamellae; branch leaves with or without comb-lamellae; stem leaves without comb-lamellae. 1 Sphagnum affine

+ Interior layer of stem cortical cells without cob-lamellae or at least not visible with a light microscope; branch leaves with comb-lamellae; stem leaves with or without comb-lamellae. (4)

4 (3) Stem leaf hyaline cells with distinct comb-lamellae; branches clavate andpointed; branches leaves strongly imbricate. Sphagnum austinii

+ Stem leaf hyaline cells with distinct comb-lamellae; branches not clavate; branch leaves more or less spreading. Sphagnum steerei

5 (1) Branch leaf chlorophyllous cells in transverse section short elliptic, elliptic to lenticular, and enclosed on both surfaces. (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. (8)

6 (5) Branch leaf chlorophyllous cells in transverse section short-elliptic and well enclosed; plants purplish red when pigmented. Sphagnum magellanicum

+ Branch leaf chlorophyllous cells in transverse section narrowly elliptic and slightly enclosed on both surfaces; plants brown when pigmented. (7)

7 (6) 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

+ 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 (5) Branch leaf hyaline cells where overlying chlorophyllous cells papillose. Sphagnum papillosum

+ Branch leaf hyaline cells where overlying chlorophyllous cells epapillose. (9)

9 (8) Superficial stem cortical cells with fibrils weak or lacking; chlorophyllous cells rectangular to truncate-elliptic, exposed equally on both surfaces. Sphagnum perichaetiale

+ Superficial stem cortical cells with strong fibrils; chlorophyllous cells triangular exposed more broadly on concave surface. (10)

10 (9) Branch leaf hyaline cells smooth throughout; pores on the convex surface elliptic to flattened-elliptic, not numerous. Sphagnum palustre

+ 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

List of lower taxa