Sphagnum papillosum |
Sphagnum obtusum |
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fat peat-moss, papillose sphagnum |
sphagnum |
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Habit | Plants moderate-sized to fairly robust; strong-stemmed and generally compact, capitulum usually not much enlarged; greenish brown to deep golden brown; forming compact carpets in floating mats and depressions as well as dense stands on hummock sides and low hummocks. | 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. |
Stem(s) | leaves to 1.3 × 0.7 mm; rarely hemiisophyllous; hyaline cells non-ornamented, mostly septate. |
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. |
Branches | generally short and blunt, leaves spreading. |
tapering or in more robust forms, frequently blunt, straight to arcuate, leaves slightly to moderately elongated at distal end. |
Branch leaves | broadly ovate, 1.7 × 1 mm; hyaline cells on convex surface with round to elliptic pores along the commissures, hyaline cell walls covered with papillae where overlying chlorophyllous cells; chlorophyllous cells trapezoidal to truncate-elliptic in transverse section, equally exposed on both surfaces or less exposed on convex surface, end walls thickened. |
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. |
Sexual condition | dioicous. |
dioicous. |
Capsule | with numerous pseudostomata. |
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Spores | 26–36 µm; more roughly papillose on distal surface than proximal surface, distinct raised, bifurcated-Y mark sculpture on distal surface; proximal laesura 0.5 spore radius or more. |
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 2–3 pendent branches.; branch stems with hyaline cells non-ornamented, no or weak funnel-like projections on the interior end walls, mostly with 1 pore per cell on superficial cell wall. |
fascicles with 2 spreading and 2 pendent branches.; branch stems green, with cortex enlarged with conspicuous retort cells. |
Sphagnum papillosum |
Sphagnum obtusum |
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Phenology | Capsules mature mid to late summer. | |
Habitat | Very common in very poor to poor fen mire habitats where it is often a major peat former, but scarce to absent in truly ombrotrophic peatlands sites | Forming carpets in minerotrophic peatlands |
Elevation | low to moderate elevations | low to moderate elevations |
Distribution |
AK; CA; CT; DE; IL; IN; MD; ME; MI; MN; NC; NH; NJ; NY; OH; OR; PA; SC; VT; WA; WI; WV; BC; NB; NF; NS; ON; PE; QC; YT; Eurasia
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AK; MN; AB; BC; MB; NF; NT; NU; ON; QC; SK; YT; Greenland; Eurasia |
Discussion | Sphagnum papillosum is often easily field-identifiable by its rich golden brown to dark brown color and short, blunt branches. Nearly all specimens have the papillae on the branch leaf chorophyll cells but a few smooth forms have been found. Such forms will have stem leaves with divided hyaline cells whereas in the confusable species S. palustre and S. centrale such cells are rare or absent. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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. 53. | FNA vol. 27, p. 73. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | S. cymbifolium var. papillosum, S. papillosum var. laeve, S. papillosum var. sublaeve, S. waghornei | |
Name authority | Lindberg: Acta Soc. Sci. Fenn. 10: 280. (1872) | Warnstorf: Bot. Zeitung (Berlin) 35: 478. (1877) |
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