Sphagnum atlanticum
Sphagnum russowii
Atlantic sphagnum
Russow's peat-moss, Russow's sphagnum
leaves triangular, large, less than 1.7 mm, mostly appressed to stem, apex weakly apiculate to narrowly obtuse;
hyaline cells efibrillose and seldom to often septate at base and sides.
leaves lingulate, 1.3–1.6 mm, apex broadly rounded or pointed and notched (sometimes denticulate), border strong and broadened at base (more than 0.25 width);
hyaline cells short sinuoid-rhombic, mostly efibrillose, 0–1(–2)-septate.
unranked, long and tapering, leaves greatly elongate at distal end.
long and slender, never 5-ranked.
ovate-lanceolate to lanceolate in aquatic forms, ovate to ovate-lanceolate in emergent forms, greater than 2.5 mm, often falcate-secund, especially in submerged forms, weakly undulate and recurved when dry;
margin entire, hyaline cells on convex surface with 0–1 pores per cell, concave surface with round wall thinnings in the cell apices and angles; chlorophyllous cells narrowly triangular in transverse section and well-enclosed on the concave surface.
ovate-lanceolate, 1.3–1.6 mm, concave, straight, apex strongly involute;
hyaline cells on convex surface with numerous round to elliptic pores along the commissures, grading from small round pores near the apex to large elliptic pores at the base, concave surface usually with large round pores throughout, but sometimes restricted to proximal portions of leaf.
dioicous.
dioicous, but some specimens apparently monoicous.
18–33 µm, coarsely papillose on both surfaces;
proximal laesura more than 0.5 spore radius.
fascicles with 2 spreading and 2 pendent branches.;
branch stem green, cortex enlarged with conspicuous retort cells.
fascicles with 2 spreading and 1–2 pendent branches.
not seen.
Sphagnum atlanticum
Sphagnum russowii
Sporophytes of Sphagnum atlanticum are rare. The other large North American Atlantic coastal plain species of sect. Cuspidata, S. torreyanum, is typically more yellow, has a more rounded capitulum, and has straight rather than subsecund branch leaves.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Sporophytes are uncommon in Sphagnum russowii. This species is associated with S. centrale, S. fallax, S. fimbriatum, S. girgensohnii, and S. squarrosum. Because of its not particularly distinct phenotype as well its strong tendency to produce hemiisophyllous stem leaves, S. russowii is probably the most frequently misidentified Sphagnum species. The combination of the flat, stellate capitulum, unranked branch leaves, and lingulate stem leaf will usually suffice to identify it. Sphagnum capillifolium has a rounded capitulum and a pointed stem leaf while S. subtile also has a rounded capitulum but a shorter and more triangular stem leaf. In montane and arctic mires it can be confused with S. warnstorfii but the latter usually has conspicuously 5-ranked branch leaves. As one might expect in such a widespread and common species, the characters can vary considerably. For example, one regularly finds plants that are consistent in every respect with the description except that they lack stem cortical pores. Some stem leaves have almost no septations in the hyaline cells while other forms have most of the cells septate. As with similar variation in the likewise common S. fuscum, there is no consistent pattern and so taxonomic recognition of the variants is unwarranted.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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