Girgensohn's Bog Moss

This species is characterized by having grayish plants with stout stems and branches and by having imbricate branch leaves and broadly ligulate stem leaves with marginal borders suddenly widened at base.

Sporophytes are uncommon in Sphagnum girgensohnii. This species is most frequently associated with S. russowii, but also found growing with S. centrale, S. fallax, S. fimbriatum, S. warnstorfii, and S. magellanicum when growing in shaded sites of mires. It is very similar to S. rubiginosum, but S. girgensohnii lacks any reddish pigments, has only 2 spreading branches per fascicle, infrequently produces sporophytes, and differs in spore morphology. Throughout much of its range, S. girgensohnii is readily recognized by its green color and its large, slender, strongly stellate capitulum. In the more northern portion of its range, it frequently forms compact stands with a golden brown color and then the stem leaf must often be examined for accurate identification. In Alaska it overlaps morphogically with S. fimbriatum subsp. concinnum, which can look very similar but will have a more spatulate stem leaf that is lacerate completely across the broad flat apex and slightly down the sides. Sphagnum girgensohnii, on the other hand, has stem leaves only lacerate for about ³/4 of the apex width and less conspicuously broadened at the apex.

Plants rather robust, stems and branches slender, stout, yellowish to grayish green, or tinged with light brownish color, in extensive compact cushions. Stem cortex in (2–)3–4 layers, hyaline cells large, thin-walled, with 2–3 large, rounded pores in each cell, without fibrils; central cylinder yellowish. Stem leaves 0.90–1.14 mm × 0.75–0.90 mm, broadly ligulate to oblong-ligulate, broadly rounded-truncate and lacerate-fringed at the apex; borders narrow above, suddenly widened below the middle (ca. 1/3 the leaf width at base); hyaline cells broadly to narrowly rhomboidal from the upper to lower, sometimes divided, without fibrils and pores, with a sieve-like triangular area of resorption at the middle of leaf base. Branches in fascicles of 3–5, with 2–3 spreading, gradually tapering or curved, sometimes short and abruptly tapering, capitulum in 5 radiate rows. Branch leaves 1.0–1.3 mm × 0.50–0.75 mm, imbricate, ovate-lanceolate, erect-spreading when dry; hyaline cells often with pseudofibrillose division, with large, rounded, unringed, central pores on the ventral surface, with small, ringed pores at the corners, rarely with commissural pores in the lower cells on the dorsal surface; green cells in cross section trapezoidal, often exposed on both surfaces, more broadly so on the ventral surface. Dioicous or monoicous; antheridial branches pale brown; perigonial buds globose. Perigonial leaves small, short and broad. Perichaetial leaves large, oblong or ovate-ligulate. Spores yellowish brown, smooth, 30–33 µm in diameter.

Plants moderate-sized to robust, open, very stiff and slender, less frequently compact, capitulum large, flat, and stellate; typically deep green in shaded sites to yellowish brown in more open sites; without metallic lustre when dry. Stems pale green to yellow-brown; superficial cortical cells with a single large round pore in distal portion of cell usually free from cell wall. Stem leaves lingulate, broadly lingulate to lingulate-spatulate; 0.8-1.3 mm, apex broad, truncate and lacerate, border broad at base (more than 0.25 of base); hyaline cells rhomboid, efibrillose, and rarely septate. Branches typically long and tapering, not 5-ranked. Branch fascicles with 2 spreading and 1-2 pendent branches. Branch stem with solitary retort cells or in groups of 2-3, necks moderately distinct. Branch leaves ovate to ovate-lanceolate, 1-1.4(-1.8) mm, concave, straight, apex strongly involute, margins entire; hyaline cells on convex surface with numerous elliptic pores along the commissures, grading from small pores near the apex to large pores near the base, concave surface with large round pores along the margins and base. Sexual condition dioicous. Spores 21-27 µm, moderately to coarsely papillose on both surfaces; proximal laesura less than 0.5 spore radius.

Distribution: China, Nepal, India, Indonesia, Korea, Japan, Russia, Caucasus, Europe, Greenland, and North America.

Habitat: in various kinds of habitats, often on wet depressions in swamps, humic soil under coniferous forests or on humic soil under Rhododendron and bamboo, sometimes on wet rocks near streams, forming large, loose carpets.

Sphagnum mehneri Warnstorf

Sphagnum girgensohnii Russow, Beitr. Torfm. 46. 1865
Sphagnum slrictum Lindb. Acta Soc. Sci. Fenn. 10: 263. 1872. Sphagnum Mehneri Wamst. Hedwigia 47: 113. 1908.
Plants sometimes short and compact, more commonly fairly robust, often very tall, green or sometimes slightly yellowish or brownish. Wood-cylinder green or yellowish or brownish; cortical cells of the stem in 2—4 layers, large, thin-waUed, without fibrils, the outer cells quadrilateral to irregularly pentagonal or hexagonal, mostly longer than broad, with a single large rounded pore in the upper end : stem-leaves large, short-lingulate, frequently as wide as long, shghtly concave, lacerate at the broad apex, with a strong border of narrow cells at the sides, broadened toward the base where the walls of its cells are pitted; hyaline cells rhomboidal, 2-3 times as long as wide in the apical part, narrower below and at the sides, without fibrils except in hemi-isophyllous forms, not divided, the membrane on the inner surface showing in apical cells large membrane-gaps occupying nearly the whole of the cell, the gaps reduced in size downward and passing into longitudinal membrane-pleats, on the outer surface the gaps more generally distributed but smaller and more nearly round: branches in fascicles of 4 or 5, 2 spreading, their cortical cells in a single layer, without fibrils, the retort-cells well developed with conspicuous necks: branch-leaves imbricate, rarely squarrose, mostly small, ovate, involute above to the toothed apex; the border entire, of 2-3 rows of narrow cells; hyaline cells fibrillose, narrowly rhomboidal, near the base 6-10 times as long as wide, shortened toward the apex to 3-4 times, on the inner surface with very numerous large rounded pores, 3-5 per cell, only in the central basal portion reduced or lacking, on the outer surface the pores very numerous, . elliptic, along the commissures, only in the middle basal part nearly of ceUwidth, 4-12 per cell: chlorophyl-cells trapezoidal in section with broader exposure on the inner surface to triangular, the lumen triangular; hyaline cells slightly or not at all convex on the inner surface, decidedly so on the outer, one fifth to one third of the diameter of the cell.
Dioicous. Antheridia in catkins on spreading branches; antheridial leaves brown, broader and shorter than the normal branch-leaves, the hyaline cells of the basal part lacking fibrils and pores. Fruiting branches erect; perichaetial leaves ovate-lingulate, the abruptly involute apex sometimes slightly lacerate, the whole leaf composed of uniform narrow cells: capsule dark-brown: spores brown-yellojv, 20-25 fi in diameter, strongly granular-roughened.
Type locality: Livonia. Russia.
Distribution: Greenland and Labrador to New Jersey; Pennsylvania; West Virginia; Ohio; Minnesota; Oregon to Alaska; also in Europe and Asia.

Sphagnum girgensohnii, also known as Girgensohn's bogmoss, Girgensohn's sphagnum or common green peat moss, is a species of peat moss with a Holarctic and Indo-Malesian distribution.