Sphagnum mississippiense |
Sphagnum obtusum |
|
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Mississippi sphagnum |
sphagnum |
|
Habit | Plants small, short and weak-stemmed, compact and sprawling in thin mats, green to pale yellow. | 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 elongate-triangular, 1.3–1.5 mm; often spreading; apex obtuse; hyaline cells mostly efibrillose and 1–septate in proximal half and lateral portions of leaves. |
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 | unranked, often blunt and with leaves moderately elongated at distal end. |
tapering or in more robust forms, frequently blunt, straight to arcuate, leaves slightly to moderately elongated at distal end. |
Branch leaves | ovate to broadly ovate at branch base and becoming ovate-lanceolate at branch tip; 1.2–1.5 mm; undulate when dry, margins serrulate; hyaline cells of convex surface with 0–5 pores or pseudopores at cell apex, concave surface with faint round wall thinnings in cell angles, but may be absent, chlorophyllous cells trapezoidal in transverse section, exposed more broadly on convex surface. |
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 | probably dioicous. |
dioicous. |
Spores | not seen. |
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 2–3 spreading and 0–2 pendent branches.; branch stems green, with cortex enlarged with conspicuous retort cells. |
fascicles with 2 spreading and 2 pendent branches.; branch stems green, with cortex enlarged with conspicuous retort cells. |
Sphagnum mississippiense |
Sphagnum obtusum |
|
Habitat | Mats in seasonally wet depressions in coastal plain | Forming carpets in minerotrophic peatlands |
Elevation | low elevations | low to moderate elevations |
Distribution |
LA; MS; NJ |
AK; MN; AB; BC; MB; NF; NT; NU; ON; QC; SK; YT; Greenland; Eurasia |
Discussion | Sporophytes of Sphagnum mississippiense are unknown. The combination of broad branch leaves and obtuse stem leaves will distinguish it from S. cuspidatum and S. viride. The much commoner and more wide-ranging S. trinitense, although also having serrulate branch leaves, has much narrower branch leaves that are more elongate at the branch tips, becoming quite lanceolate as compared with the ovate-lanceolate branch leaves that S. mississippiense exhibits at its branch tips. (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. 73. | FNA vol. 27, p. 73. |
Parent taxa | ||
Sibling taxa | ||
Name authority | R. E. Andrus: Mem. New York Bot. Gard. 45: 237. 1987 (as mississippiensis), | Warnstorf: Bot. Zeitung (Berlin) 35: 478. (1877) |
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