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BFNA | Family List | BFNA Vol. 1 | Sphagnaceae | Sphagnum

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

Authors: Richard E. Andrus

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 ┬Ám, 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

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