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sphagnum

Habit Plants moderate to robust, weak-stemmed, yellow, yellowish brown to golden brown; capitulum varying from rounded, not 5-radiate and twisted to flat 5-radiate and straight branched. Plants moderate-sized; capitulum flat-topped and dense; pale yellow and pink, lacking sheen.
Stem

pale green to pale brown;

superficial cortex of weakly to moderately differentiated.;

stem leaves triangular-lingulate, 0.9–1.3 mm; usually appressed;

apex obtuse and often erose;

hyaline cells efibrillose and nonseptate.

pink, superficial cortical cells aporose.;

stem leaves narrowly triangular to lingulate- triangular, 1.2–1.6 × 0.6–0.8 mm, length: width ratio ca. 2:1, apex apiculate, border strong and moderately broadened basally;

hyaline cells narrowly rhomboid and 1 to occasionally 2 septate, often fibrillose apically.

Branches

tapering or in more robust forms, frequently blunt, straight to arcuate, leaves slightly to moderately elongated at distal end.

not 5-ranked.

Branch leaves

ovate to ovate-lanceolate; more than 1.8 mm; straight, stiff, not much undulate and reflexed to recurved;

margins entire;

hyaline cells on convex surface with a few end pores, but mostly numerous small to very small (often barely visible) pores or wall thinnings free from the commissures, on concave surface similar, but with pores generally fewer and larger; chlorophyllous cells triangular in transverse section, just reaching concave surface or slightly enclosed.

1.3–1.5 × 0.5–0.55 mm, ovate-lanceolate, concave, straight, apex involute;

hyaline cells on convex surface with numerous round to elliptic pores along the commissures, grading from large elliptical pores at the base to moderate-sized round pores at the apex, concave surface with a few large round pores scattered throughout.

Sexual condition

dioicous.

unknown.

Spores

18–27 µm;

both surfaces covered with rough, irregular verrucate plates of papillae, bifurcated Y-mark sculpture on distal surface;

proximal laesura less than 0.5 spore radius.

Branch

fascicles with 2 spreading and 2 pendent branches.;

branch stems green, with cortex enlarged with conspicuous retort cells.

fascicles with 2 spreading and 1 pendent branch.

Sphagnum obtusum

Sphagnum sitchense

Habitat Forming carpets in minerotrophic peatlands Known only from type locality where it was forming low dense hummocks in alpine tundra
Elevation low to moderate elevations moderate elevations
Distribution
from FNA
AK; MN; AB; BC; MB; NF; NT; NU; ON; QC; SK; YT; Greenland; Eurasia
from FNA
AK
Discussion

Sporophytes are uncommon in Sphagnum obtusum. This is a quite phenotypically variable species that warrants further investigation, which may result in taxonomic splitting. The strongly obtuse stem leaf should separate it from any similar species with which it occurs. Sphagnum mendocinum looks similar phenotypically but there appears to be no range overlap with S. obtusum. The tiny branch leaf pores, which may seem like no more than pinpricks in the cell surface, easily separate S. obtusum microscopically from other species of sect. Cuspidata.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 27, p. 73. FNA vol. 27, p. 98.
Parent taxa Sphagnaceae > Sphagnum > sect. Cuspidata Sphagnaceae > Sphagnum > sect. Acutifolia
Sibling taxa
S. affine, S. alaskense, S. andersonianum, S. angermanicum, S. angustifolium, S. annulatum, S. aongstroemii, S. arcticum, S. atlanticum, S. austinii, S. balticum, S. bartlettianum, S. beothuk, S. bergianum, S. brevifolium, S. capillifolium, S. carolinianum, S. centrale, S. compactum, S. contortum, S. cribrosum, S. cuspidatum, S. cyclophyllum, S. fallax, S. fimbriatum, S. fitzgeraldii, S. flavicomans, S. flexuosum, S. fuscum, S. girgensohnii, S. henryense, S. imbricatum, S. inexspectatum, S. inundatum, S. isoviitae, S. jensenii, S. junghuhnianum, S. kenaiense, S. lenense, S. lescurii, S. lindbergii, S. macrophyllum, S. magellanicum, S. majus, S. mcqueenii, S. mendocinum, S. microcarpum, S. mirum, S. mississippiense, S. molle, S. oregonense, S. orientale, S. pacificum, S. palustre, S. papillosum, S. perfoliatum, S. perichaetiale, S. platyphyllum, S. portoricense, S. pulchrum, S. pylaesii, S. quinquefarium, S. recurvum, S. riparium, S. rubellum, S. rubiginosum, S. rubroflexuosum, S. russowii, S. sitchense, S. splendens, S. squarrosum, S. steerei, S. strictum, S. subfulvum, S. subnitens, S. subsecundum, S. subtile, S. talbotianum, S. tenellum, S. tenerum, S. teres, S. torreyanum, S. trinitense, S. tundrae, S. viride, S. warnstorfii, S. wilfii, S. wulfianum
S. affine, S. alaskense, S. andersonianum, S. angermanicum, S. angustifolium, S. annulatum, S. aongstroemii, S. arcticum, S. atlanticum, S. austinii, S. balticum, S. bartlettianum, S. beothuk, S. bergianum, S. brevifolium, S. capillifolium, S. carolinianum, S. centrale, S. compactum, S. contortum, S. cribrosum, S. cuspidatum, S. cyclophyllum, S. fallax, S. fimbriatum, S. fitzgeraldii, S. flavicomans, S. flexuosum, S. fuscum, S. girgensohnii, S. henryense, S. imbricatum, S. inexspectatum, S. inundatum, S. isoviitae, S. jensenii, S. junghuhnianum, S. kenaiense, S. lenense, S. lescurii, S. lindbergii, S. macrophyllum, S. magellanicum, S. majus, S. mcqueenii, S. mendocinum, S. microcarpum, S. mirum, S. mississippiense, S. molle, S. obtusum, S. oregonense, S. orientale, S. pacificum, S. palustre, S. papillosum, S. perfoliatum, S. perichaetiale, S. platyphyllum, S. portoricense, S. pulchrum, S. pylaesii, S. quinquefarium, S. recurvum, S. riparium, S. rubellum, S. rubiginosum, S. rubroflexuosum, S. russowii, S. splendens, S. squarrosum, S. steerei, S. strictum, S. subfulvum, S. subnitens, S. subsecundum, S. subtile, S. talbotianum, S. tenellum, S. tenerum, S. teres, S. torreyanum, S. trinitense, S. tundrae, S. viride, S. warnstorfii, S. wilfii, S. wulfianum
Name authority Warnstorf: Bot. Zeitung (Berlin) 35: 478. (1877) R. E. Andrus: Sida 22: 969, figs. 27–34. (2006)
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