Sphagnum obtusum |
Sphagnum cribrosum |
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sphagnum |
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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 green, light brown to brown. |
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. |
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Branches | tapering or in more robust forms, frequently blunt, straight to arcuate, leaves slightly to moderately elongated at distal end. |
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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. |
ovate-ligulate, apex broad, rounded, and truncate, hyaline cells with 20–40 small (less than 0.25 cell diameter) in mostly 2 rows. |
Sexual condition | dioicous. |
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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. |
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Branch | fascicles with 2 spreading and 2 pendent branches.; branch stems green, with cortex enlarged with conspicuous retort cells. |
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Sphagnum obtusum |
Sphagnum cribrosum |
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Habitat | Forming carpets in minerotrophic peatlands | Floating or stranded at margins of shallow acidic lakes and ponds |
Elevation | low to moderate elevations | low elevations |
Distribution |
AK; MN; AB; BC; MB; NF; NT; NU; ON; QC; SK; YT; Greenland; Eurasia |
FL; GA; MD; NC; SC |
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.) |
Besides having different branch leaf porosity, Sphagnum cribrosum is usually distinguishable from the closely related S. macrophyllum by its paler brown color and distinctly broader and more truncate branch leaves. “Wave forms” of both S. cribrosum and S. macrophyllum, seemingly developed in response to growing in shallow water where wave action is common, can have very odd phenotypes that may look more like Fontinalis than Sphagnum. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 27, p. 73. | FNA vol. 27, p. 61. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | S. floridanum, S. macrophyllum var. floridanum | |
Name authority | Warnstorf: Bot. Zeitung (Berlin) 35: 478. (1877) | Lindberg: Eur. Hvitmoss., 74. (1882) |
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