Sphagnum obtusum |
Sphagnum inexspectatum |
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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 moderate-sized, normally erect; yellowish to reddish brown, greenish in shaded forms; capitulum moderately distinct and rounded. |
Stem(s) | 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. |
leaves triangular-lingulate to ovate-lingulate, 0.8–0.9 mm, apex rounded, straight; hyaline cells mostly non-septate, fibrillose in distal 1/3–2/3 of leaf, a few ringed pores at corners of cells and along commissures on convex surface, ringed pores along the commissures on the concave surface in greater numbers than on convex surface. |
Branches | tapering or in more robust forms, frequently blunt, straight to arcuate, leaves slightly to moderately elongated at distal end. |
short, not turgid. |
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. |
broad-ovate to ovate-lanceolate, 0.9–2.1 mm, straight; hyaline cells with numerous ringed pores (10–20) along the commissures on the convex surface, a few pseudopores and ringed pores (less than 8 per cell) occur on the cell angles on the concave surface. |
Sexual condition | dioicous. |
dioicous. |
Capsule | exserted, with few pseudostomata. |
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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. |
36–39 µm; coarsely papillose on both surfaces; proximal laesura less than or equal to 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 2–3 spreading and 1–2 pendent branches. |
Sphagnum obtusum |
Sphagnum inexspectatum |
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Habitat | Forming carpets in minerotrophic peatlands | Ecology unclear, but growing in carpets in depressions, blanket mires |
Elevation | low to moderate elevations | low to moderate elevations |
Distribution |
AK; MN; AB; BC; MB; NF; NT; NU; ON; QC; SK; YT; Greenland; Eurasia |
AK; BC; Asia |
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.) |
Sphagnum inexpectatum is frequently collected with S. tenellum, S. pacificum, S. andersonianum, and S. rubellum in weakly minerotrophic blanket mires. It is similar in size to S. subsecundum, with which its range completely overlaps. The latter species has many of the branch leaves subsecund while those of S. inexspectatum are straight. The stem leaves of S. inexspectatum are also conspicuously larger than those of S. subsecundum. Microscopically Sphagnum inexspectatum has a stem cortex that has enlarged thin-walled cells that form 1–2 layers, whereas S. subsecundum has only one. The stem leaves of S. inexspectatum also have numerous commissural pores in the hyaline cells in the distal half of the concave surface, whereas S. subsecundum has only a few if any in this region and these are more free than commissural. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 27, p. 73. | FNA vol. 27, p. 80. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | S. subsecundum var. andrusii, S. subsecundum var. junsaiense | |
Name authority | Warnstorf: Bot. Zeitung (Berlin) 35: 478. (1877) | Flatberg: Lindbergia 30: 59. (2005) |
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