Sphagnum sect. Cuspidata

Plants varying from lax, free-floating forms to compact terrestrial forms, usually with distinct capitulum; green, whitish, pale, yellow-green to light brownish, rarely dark-colored. Stems green, brown, dark brown to occasionally pinkish in parts, superficial cortex of 0–4 layers of efibrillose, non-ornamented, enlarged, thin-walled cells, cells in outer layer aporose. Stem leaves usually smaller than branch leaves, triangular to lingulate, apex apiculate, acute, broad, or erose and split, border narrow or broad at base; hyaline cells non-ornamented, usually efibrillose (in proximal portion) to often fibrillose in distal portion of leaf, aporose or with few pores and septate to nonseptate. Branches dimorphic, pendent branches more slender and delicate than spreading branches. Branch fascicles with 2–3 spreading to 1–3 pendent branches. Branch stems green to pinkish, surrounded by 1 layer of efibrillose, non-ornamented, enlarged, thin-walled cells, with solitary uniporose retort cells (or in groups) with short necks, other aporose cells rectangular. Branch leaves usually longer than stem leaves, ovate to lanceolate; margins entire or in a few cases serrulate; apex involute and smooth; hyaline cells non-ornamented, fibrillose (in one case efibrillose), convex surface porose or with a few to numerous pores or pseudopores, concave surface aporose or with pores or pore-like wall thinnings; chlorophyllous cells triangular to trapezoidal in transverse section, more broadly exposed on convex surface, end walls not thickened. Sexual condition mostly dioicous or occasionally monoicous. Capsule less than 2 mm, with few pseudostomata. Spores usually more than 30 µm, rarely with raised surface sculpture on distal surface; proximal laesura typically less than or equal to 0.5 spore radius.

Distribution

Worldwide except Antarctica.

Discussion

Species ca. 55 (29 in the flora).

Selected References

None.

Lower Taxa

Sphagnum angustifolium, Sphagnum annulatum, Sphagnum atlanticum, Sphagnum balticum, Sphagnum brevifolium, Sphagnum cuspidatum, Sphagnum fallax, Sphagnum fitzgeraldii, Sphagnum flexuosum, Sphagnum isoviitae, Sphagnum jensenii, Sphagnum kenaiense, Sphagnum lenense, Sphagnum lindbergii, Sphagnum majus, Sphagnum mcqueenii, Sphagnum mendocinum, Sphagnum mississippiense, Sphagnum obtusum, Sphagnum pacificum, Sphagnum pulchrum, Sphagnum recurvum, Sphagnum riparium, Sphagnum rubroflexuosum, Sphagnum splendens, Sphagnum tenellum, Sphagnum torreyanum, Sphagnum trinitense, Sphagnum viride

Key

1	Stem leaves lacerate across all or part of apex	> 2
1	Stem leaves erose to entire at apex	> 4
2	Stem leaves lingulate-spatulate, lacerate across broad apex and partially down the sides.	Sphagnum lindbergii
2	Stem leaves lingulate to triangular-lingulate, lacerate or notched in middle of apex only	> 3
3	Stem leaves lingulate; branch leaves not sharply recurved when dry and typically strongly 5-ranked; plants strongly brown-pigmented, small and compact.	Sphagnum lenense
3	Stem leaves triangular-lingulate; branch leaves sharply recurved when dry and rarely 5-ranked; plants typically green, large and not especially compact.	Sphagnum riparium
4	Branch leaf hyaline cells efibrillose.	Sphagnum splendens
4	Branch leaf hyaline cells fibrillose	> 5
5	Branch leaf hyaline cells with 5 or more free pores per cell in proximal portion of convex surface	> 6
5	Branch leaf hyaline cells with less than 5 free pores per cell in proximal portion of convex surface	> 12
6	Branch leaf hyaline cells lacking pores or wall thinnings on concave surface.	Sphagnum majus
6	Branch leaf hyaline cells with pores or wall thinnings on concave surface	> 7
7	Branch leaf hyaline cells with round wall thinnings in the cell angles and apices on the concave surface	> 8
7	Branch leaf hyaline cells with pores or wall thinnings free from the cell margins on the concave surface	> 10
8	Stem leaves fibrillose at apex; stem leaves spreading at right angles; common species of northern peatlands.	Sphagnum balticum
8	Stem leaves normally efibrillose and appressed but sometimes spreading	> 9
9	Branch leaves ovate, stem cortex well-differentiated but not enlarged	Sphagnum kenaiense
9	Branch leaves ovate-lanceolate, stem cortex undifferentiated	Sphagnum rubroflexuosum
10	Stem leaves lingulate to triangular-lingulate and with a more or less erose apex; branch leaf pores faint (visible only with heavy staining).	Sphagnum obtusum
10	Stem leaves triangular and with an obtuse, entire apex; branch leaf pores obvious	> 11
11	Branch leaf hyaline cells with numerous free pores on convex surface in distal region, branch leaf hyaline cells relatively short and wide in proximal portion.	Sphagnum annulatum
11	Branch leaf hyaline cells with numerous pseudopores along commissures on convex surface in distal region; branch leaf hyaline cells relatively long and narrow in proximal portion.	Sphagnum jensenii
12	Branch leaves with numerous pores along the commissures on both surfaces, round wall thinnings in cell angles and apices not present on concave surface.	Sphagnum mendocinum
12	Branch leaves with few or no pores along the commissures on either surface; round wall thinnings present in cell angles and apices on concave surface	> 13
13	Stem leaves lingulate to ovate-lingulate and with incurved distal margins	> 14
13	Stem leaves various but not as above	> 15
14	Branch leaves ovate to ovate-lanceolate, moderately concave, slightly undulate and recurved, often 5-ranked.	Sphagnum balticum
14	Branch leaves ovate, strongly concave, neither undulate nor recurved, not 5-ranked	Sphagnum tenellum
15	Branch leaves with serrulate margins	> 16
15	Branch leaves entire along margins	> 18
16	Branch leaves with broad, rounded apex.	Sphagnum fitzgeraldii
16	Branch leaves with pointed involute apex	> 17
17	Branch leaves ovate to broadly ovate; spreading branches short, little tapered to distal end.	Sphagnum mississippiense
17	Branch leaves ovate-lanceolate to lanceolate; spreading branches long, tapered to distal end.	Sphagnum trinitense
18	Stem leaves lingulate to triangular-lingulate with more or less erose apex	> 19
18	Stem leaves triangular to triangular-lingulate, acute to obtuse but rarely erose	> 22
19	Branch leaves sharply recurved when dry; stem leaves efibrillose at apex.	Sphagnum recurvum
19	Branch leaves slightly recurved when dry; stem leaves efibrillose or fibrillose at apex	> 20
20	Stem leaves spreading, fibrillose distally.	Sphagnum balticum
20	Stem leaves appressed, efibrillose distally	> 21
21	Branch leaves ovate-lanceolate, stem cortex undifferentiated.	Sphagnum flexuosum
21	Branch leaves ovate, stem cortex well-differentiated but not enlarged	Sphagnum kenaiense
22	Stem leaves less than 0.8 mm, triangular.	Sphagnum angustifolium
22	Stem leaves 0.8 mm or more (if shorter, then apiculate), triangular to triangular-lingulate	> 23
23	Branch leaves typically broadly ovate with an abruptly involute apex.	Sphagnum pulchrum
23	Branch leaves ovate-lanceolate to lanceolate with a tapered involute apex	> 24
24	Stem leaves apiculate; young pendent branches in pairs between rays of the capitulum; carpet forming species with branch leaves not greatly elongated at distal branch end	> 25
24	Stem leaves obtuse to apiculate; young pendent branches not in pairs between the branches of the capitulum; aquatic species with branch leaves substantially elongated at distal branch end	> 28
25	Branch leaves strongly recurved when dry	> 26
25	Branch leaves weakly recurved when dry	> 27
26	Branch leaf chlorophyll cells slightly enclosed on or just reaching concave surface; stem cortex with moderately enlarged and thick- walled cells.	Sphagnum fallax
26	Branch leaf chlorophyll cells wall-enclosed on concave surface; stem cortex with strongly enlarged thin-walled cells.	Sphagnum pacificum
27	Branch leaves relatively broad, with length to width ratio ca. 2.8; stem leaves relatively narrow, with length to width ratio ca. 1:1.22; branch leaves unranked or only weakly 5-ranked.	Sphagnum brevifolium
27	Branch leaves relatively narrow, with length to width ratio ca. 3.2; stem leaves relatively broad, with length to width ratio 1:1.14; branch leaves typically strongly 5-ranked	Sphagnum isoviitae
28	Branch leaf chlorophyll cells very well-enclosed on concave surface	> 29
28	Branch leaf chlorophyll cells slightly enclosed or reaching concave surface	> 30
29	Branch leaf chlorophyll cells in transverse section well-enclosed and reaching only ca. 1/2 the distance to the concave surface; branch leaves often falcate-secund	Sphagnum atlanticum
29	Branch leaf chlorophyll cells slightly enclosed and reaching about 3/4 the distance to the concave surface; branch leaves typically straight.	Sphagnum torreyanum
30	Stem leaves obtuse, spreading and with septate hyaline cells in the proximal mid region.	Sphagnum mcqueenii
30	Stem leaves acute to apiculate, appressed and with non-septate hyaline cells in proximal mid region	> 31
31	Branch leaves relatively narrow, length to width equal or greater than 3.6:1, hyaline cells in distal region convex surface 8-15:1; capitulum often twisted.	Sphagnum cuspidatum
31	Branch leaves relatively broad, length to width less than 3.6:1, hyaline cells in distal region convex surface 4-8:1; capitulum with straight branches.	Sphagnum viride