Sphagnum sect. Acutifolia

Plants small to moderate-sized, rarely robust, with distinct capitulum; green, brown, pink, red. Stems green, red or brown, superficial cortex of 2–4 layers of efibrillose, non-ornamented, inflated, thin-walled cells, mostly aporose, but may be porose in some species. Stem leaves similar in size to branch leaves; varying from triangular to lingulate-spatulate; apex varying from acute and entire to very broad and lacerate; border entire or, in one case, fimbriate; hyaline cells rhomboid to S-shaped, non-ornamented, efibrillose or fibrillose, aporose or in hemiisophyllous forms porose, 0–2-septate, mostly resorbed on interior surface and mostly entire on exterior surface. Branches dimorphic, spreading branches usually longer and thicker than pendent branches. Branch fascicles with 2(–3) spreading and 1–2 pendent branches. Branch stems green, surrounded by 1 layer of efibrillose, non-ornamented, inflated, thin-walled hyaline cells, some solitary or in groups of uniporose retort cells, with more or less conspicuous necks. Branch leaves ovate to ovate-lanceolate, margins entire or, in one case, toothed, involute near smooth apex; hyaline cells efibrillose, non-ornamented, with round to elliptic pores along commissures on convex surface, fewer, larger and round mostly free pores on concave surface; chlorophyllous cells triangular to trapezoidal in transverse section, more broadly exposed on concave surface, end walls not thickened. Sexual condition usually dioicous, occasionally monoicous. Capsule equal to or less than 2 mm, with few to many pseudostomata. Spores typically less than 30 µm, coarsely to finely papillose on both surfaces, may have raised surface sculpture on distal surface; proximal laesura typically less than or equal to 0.5 spore radius.

Distribution

Worldwide except Antarctica.

Discussion

Species 60 (25 in the flora).

Selected References

None.

Lower Taxa

Sphagnum andersonianum, Sphagnum angermanicum, Sphagnum arcticum, Sphagnum bartlettianum, Sphagnum beothuk, Sphagnum bergianum, Sphagnum capillifolium, Sphagnum fimbriatum, Sphagnum flavicomans, Sphagnum fuscum, Sphagnum girgensohnii, Sphagnum junghuhnianum, Sphagnum molle, Sphagnum quinquefarium, Sphagnum rubellum, Sphagnum rubiginosum, Sphagnum russowii, Sphagnum sitchense, Sphagnum subfulvum, Sphagnum subnitens, Sphagnum subtile, Sphagnum talbotianum, Sphagnum tenerum, Sphagnum warnstorfii, Sphagnum wilfii

Key

1	Branch leaves with denticulate margin along a resorption furrow.	Sphagnum molle
1	Branch leaf margins plain and bordered without a resorption furrow	> 2
2	Stem leaves with broad lacerate to fimbriate apex	> 3
2	Stem leaves with acute, slightly toothed, notched, erose, or rounded apex	> 11
3	Stem leaves with broad, lacerate apex equal to or less than one half the width of the leaf	> 4
3	Stem leaves with broad lacerate apex greater or equal to one half the width of the leaf	> 7
4	Plants red-pigmented	> 5
4	Plants brown-pigmented, branch leaves ovate-lanceolate and relatively shallow or moderately concave	> 6
5	Branch leaves ovate and deeply concave, stem cortex aporose	Sphagnum andersonianum
5	Branch leaves ovate-lanceolate and only slightly concave, stem cortex usually porose	Sphagnum russowii
6	Branch leaves greater than 1.4 mm.	Sphagnum arcticum
6	Branch leaves less than 1.4 mm.	Sphagnum fuscum
7	Stem leaves spatulate, fimbriate to lacerate across broad apex and along the margins for one-half or more the length; plants slender with conspicuous terminal bud and frequently with numerous sporophytes.	Sphagnum fimbriatum
7	Stem leaves lingulate, fimbriate across the apex; plants small to moderate-sized and rigid, terminal bud if present not conspicuous, sporophytes may or may not be present	> 8
8	Branch fascicles of three spreading and one to two pendent branches; plants green to variegated green and red or red-brown, sporophytes usually present.	Sphagnum rubiginosum
8	Branch fascicles of two spreading and one to two pendent branches; plants green or variegated green and brown or golden brown, sporophytes usually not present	> 9
9	Surface cells of the stem predominately aporose, but some cells with one elliptical pore at distal cell end; branch leaves longer than 1.4 mm; stem leaves usually longer than 1.2 mm; plants typically brown to dark brown.	Sphagnum arcticum
9	Surface cells of the stem usually porose with a single elliptical pore in distal portion of cell, but usually free from the cell end wall; branch leaves shorter than 1.4 mm; most stem leaves shorter than 1.2 mm; plants green to brown	> 10
10	Stem leaf hyaline cells frequently septate, strongly so along margins in upper half.	Sphagnum fimbriatum
10	Stem leaves only occasionally septate.	Sphagnum girgensohnii
11	Plants brown colored; stem brown in green forms	> 12
11	Plants red, purple-red; stem green, yellow-green, red or pink in green forms	> 18
12	Plants without conspicuous metallic sheen when dry	> 13
12	Plants with metallic sheen when dry	> 15
13	Stem leaves lingulate; branch leaves equal to or less than 1.3 mm; plants small	Sphagnum fuscum
13	Stem leaves lingulate- triangular, broadly ovate-triangular to sublingulate; branch leaves greater than 1.3 mm, plants moderate in size	> 14
14	Stem leaves lingulate-triangular, 1.5-2 mm, apex right angled to apiculate, retort cells with conspicuous neck; northeastern North American coastal regions south to Delaware.	Sphagnum flavicomans
14	Stem leaves broadly oblong-ovate to sublingulate, 1.2-1.8 mm, apex broadly acute to narrowly truncate and toothed; branch leaves loosely arranged and spreading, abruptly involute-acuminate in distal third of leaf from ovate to elliptic base, 1.3-2 mm; retort cells with very short or no noticeable neck; one known locality, in British Columbia.	Sphagnum junghuhnianum
15	Branch leaves 5-ranked; stem leaves with rounded apices frequently fimbriate, plants very dark brown	> 16
15	Stem leaves unranked, with hyaline cells rarely more than once septate and apices rarely fimbriate	> 17
16	Plants with purplish tinge; stem leaves lingulate, hyaline cells in middle of leaf 0-1-septate.	Sphagnum beothuk
16	Plants with deep red tinge; stem leaves triangular-lingulate, hyaline cells in middle of leaf 1-2-septate	Sphagnum bergianum
17	Stem leaves lingulate-triangular to lingulate, 1-1.5 mm, apex broadly rounded to obtusely angled, and sometimes apiculate, border strongly broadened at base; branch leaves 1.2-1.7 mm, ovate-lanceolate and short-pointed; plants yellowish brown to dark brown.	Sphagnum subfulvum
17	Stem leaves oblong-triangular, 1.3-1.7 mm, apex broadly acute and usually narrowed to a concave cuspidate point, border slightly broadened at based; branch leaves 1.5-2 mm, narrow-lanceolate, apex recurved when dry; plants yellow-brown and tinged with pink to purplish red	Sphagnum subnitens
18	Branch leaf hyaline cells in apical region of abaxial surface with very small (less than 2 µm), round, strongly ringed pores; branch leaves strongly 5-ranked.	Sphagnum warnstorfii
18	Branch leaf hyaline cells in apical region on abaxial surface with moderate to large (more than 3 µm) pores, with moderate to no observable rings; branch leaves variously ranked	> 19
19	Stem leaves triangular to triangular-lingulate	> 20
19	Stem leaves variously shaped, but not triangular to triangular-lingulate, border thickness various at base	> 22
20	Branch leaves strongly 5-ranked.	Sphagnum quinquefarium
20	Branch leaves unranked	> 21
21	Stem leaves not strongly bordered basally, 1 hanging branch per fascicle	Sphagnum sitchense
21	Stem leaves strongly bordered basally, 2 hanging branches per fascicle.	Sphagnum subtile
22	Stem leaves lingulate to spatulate, broadest above middle, toothed across broad truncate apex; branch leaves oblong-ovate to elliptic, 1.3-2 mm, with 6-12 teeth across broad apex	Sphagnum angermanicum
22	Stem leaves variously shaped, broadest at base; branch leaves with few or no teeth across narrow apex	> 23
23	Outer stem cortical cells porose.	Sphagnum russowii
23	Outer stem cortical cells aporose	> 24
24	Branch leaves 5-ranked	> 25
24	Branch leaves unranked	> 28
25	Stem leaves usually less than 1.1 mm.	Sphagnum talbotianum
25	Stem leaves usually more than 1.1 mm	> 26
26	Stem leaves broadly triangular to triangular-lingulate; branch leaves straight.	Sphagnum wilfii
26	Stem leaves lingulate to lingulate-triangular; branch leaves straight to subsecund	> 27
27	Stem leaves narrowly lingulate-triangular, 1.2-1.8 mm, margins nearly parallel for 3/4 the length of the leaf, apex acute to apiculate, weakly to moderately broadened border at base with the total stem leaf border width less than 0.2 mm; stem leaf hyaline cells rhombic in shape and 0-1-septate; branch leaves narrowly ovate-lanceolate and nearly all straight.	Sphagnum bartlettianum
27	Stem leaves lingulate to lingulate-triangular, 1.2-1.5 mm, margins not strictly parallel in proximal portion of leaf, apex broadly rounded, acute in hemiisophyllous forms, strongly bordered at base with the total stem leaf border width usually greater than 0.2 mm; stem leaf hyaline cells rhombic in shape and with at least some in the middle of leaf 2-septate; branch leaves ovate to ovate-lanceolate and falcate-secund on at least some branches.	Sphagnum rubellum
28	Branch fascicles with nearly all having two spreading and one pendent branch; branch leaves small, usually less than 1.1 mm, ovate and concave; stem leaves lingulate, usually less than 1.2 mm, apex rounded to slightly apiculate; capitulum diameter usually less than 2.8 mm.	Sphagnum andersonianum
28	Branch fascicles of two spreading and two pendent branches, some fascicles with a single pendent branch; branch leaves moderate in size, longer than 1.1 mm, ovate to ovate-lanceolate, not particularly strongly concave; stem leaves elongate triangular-lingulate, usually longer than 1.2 mm, apex acute and usually toothed; capitulum diameter usually greater than 3 mm	> 29
29	Plants with conspicuous metallic sheen when dry.	Sphagnum subnitens
29	Plants lacking conspicuous metallic sheen when dry	> 30
30	Stem leaves variously fibrillose or efibrillose, triangular- lingulate, small to moderate in size (1.2-1.4 mm, 0.5-0.8 mm wide at base), border at base moderately broadened with a total border width of 0.15-0.25 mm; branch leaves ovate-lanceolate, 1.1-1.4 mm, large round pores restricted to proximal sides and portions of adaxial surface.	Sphagnum capillifolium
30	Stem leaves usually fibrillose throughout, elongate-triangular to elongate triangular-ovate, moderate in size (1.3-1.7 mm, 0.3-0.4 mm wide at base), border at base only slightly broadened with total border width of 0.15 mm or less; branch leaves ovate, 1.2-1.7 mm, large round pores throughout adaxial surface.	Sphagnum tenerum