Recurved Sphagnum

Sporophytes in Sphagnum recurvum are uncommon. This species is found exclusively in the New World. It has several strong characters that distinguish it from S. flexuosum, and the opinion of H. A. Crum (1997) that the two species are synonymous is rejected. See discussion under 30. S. flexuosum.

Plants rather large, slender, to 20 cm high, bright green to yellowish green or sometimes brown, in loose tufts. Stem cortex in 2–4 layers, indistinct, hyaline cells thick-walled, without fibrils and pores; central cylinder not much differentiated from cortical layers, green or yellowish green. Stem leaves 0.5–1.0 mm × 0.5–1.0 mm, nearly equilateral-triangular, with abruptly pointed apex or strongly lacerate across the apex; borders narrow above, gradually widened below the middle; hyaline cells undivided, mostly without fibrils and pores. Branches in fascicles of 3–5, with 1–2 spreading. Branch leaves 0.8–3.0 mm × 0.3–1.0 mm, ovate-lanceolate to lanceolate, strongly concave and cucullate near the apex, often cucullate-recurved in the apex when dry; borders narrow; hyaline cells with rather large, rounded, unringed pores at the corners on the ventral surface, with a few small pores at the corners or along commissural rows, often becoming larger near the base on the dorsal surface; green cells in cross section isosceles-triangular, exposed on the dorsal surface, enclosed by hyaline cells on the ventral surface. Dioicous; antheridial branches brownish orange; perigonial leaves oblong-elliptic with a broad base and an apiculate apex. Perichaetial leaves large, broadly ovate, abruptly sharp pointed at the apex, borders wide, almost consisting of all green cells near the base. Spores yellowish, smooth or papillose, ca. 25 µm in diameter.

Plants moderate-sized to robust, moderately stiff-stemmed, ± lax, but not compact; green to pale yellow to yellowish brown; capitulum typically strongly convex in open grown forms, but flat and ± 5-radiate in shade forms. Stem pale green to yellowish; superficial cortex of 2 layers of enlarged, thin-walled and well differentiated cells. Stem leaves triangular, triangular-lingulate to lingulate, more than 0.8 mm, appressed, apex obtuse to broadly obtuse, erose to fimbriate; hyaline cells efibrillose and nonseptate. Branches straight and often tapering, often 5-ranked, leaves not much elongate at distal end of branches. Branch fascicles with 2 spreading and 2 pendent branches. Branch stems green, cortex enlarged with conspicuous retort cells. Branch leaves ovate-lanceolate, 1.4-2 mm, straight; slightly undulate and sharply recurved; margins entire; hyaline cells on convex surface with 1 pore per cell at cell apex, concave surface with round wall thinnings in the cell ends and angles; chlorophyllous cells triangular in transverse section and well-enclosed on concave surface. Sexual condition dioicous. Spores 22-28 µm; papillose on both surfaces; proximal laesura more than 0.5 spore radius.

Distribution: China, Nepal, India, Japan, Russia (Siberia), Europe, North America, and New Zealand.

Habitat: usually in bogs, hummocks or on wet ground under coniferous forests.

Sphagnum recurvum ssp. amblyphyllum Russ., Sitzungsber. Naturf.-Ges. Dorpat 9: 99. 1890. Sphagnum recurvum var. amblyphyllum (Russ.) Warnst., Bot. Gaz. 15: 219. 1890. Sphagnum amblyphyllum (Russ.) Zick., Bull. Soc. Nat. Mosc., II, 14: 278. 1900. Sphagnum amblyphyllum (Russ.) Warnst., Sphagn. Univ. 212. 1911, hom. illeg. Sphagnum flexuosum Dozy & Molk., Prodr. Fl. Bat. 2(1): 76. 1851. Sphagnum flexuosum var. recurvum Dozy & Molk., Prodr. Fl. Bat. 2(1): 77. 1851.

Sphagnum pentastichon Bridel; S. pulchricoma Müller Hal.; S. riparioides Warnstorf

Sphagnum recurvum Beauv. Prodr. Aetheog. 88. 1805
Sphagnum pulchricoma CMuW.Syn. : 102. 1848.
Sphagnum fallax H. Klinggr. Topogr. Fl. Westpr. 128. 1880.
5p/iagnum ri/)ario!(i(ri Wamst. Hedwigia 47: 118. 1908. ^
Sphagnum amblyphyllum Wamst. in Engler, Pflanzenreich Sphag. 212. 1911.
Plants commonly more or less robust, bright-green or sometimes tinged yellowish or brownish. Wood-cylinder yellowish-green; cortical cells of the stem slightly if at all differentiated, the outer cells of the stem elongate-quadrilateral, without fibrils or pores: stemleaves very small, triangular to triangular-Iingulate, the apex mucronate to rounded or truncate, sometimes slightly eroded, the border of narrow cells with pitted walls occupying nearly the whole breadth of the leaf toward the base; hyaline cells rathei short, not divided, normally without fibrils, their cell-membrane on the inner surface mostly resorbed in the cells of the apical part, the gaps decreasing in size downward and toward the side-region and passing into longitudinal membrane-pleats, on the outer surface resorbed only in the cells of the immediate apex: branches normally in fascicles of 5, 2 spreading, their cortical cells in a single layer, the retortcells with inconspicuous necks: branch-leaves undulate when dry with spreading tips, narrowly lanceolate, involute toward the toothed apex, the border entire, of 2-4 rows of very narrow cells: hyaline cells fibrillose, narrowly linear-rhomboidal, in the basal portion 10-12 times as long as wide, shorter above to 6-7 times, on the inner surface with numerous large rounded pores in the angles and near the commissures, 4-7 per cell, on the outer surface with endpores throughout, in the apical portion with small ringed pores also in the angles and near the commissures, accordingly 2-6 per cell: chlorophyl-cells triangular in section with the base of the triangle exposed on the outer surface of the leaf, its apex reaching the inner surface or slightly included ; hyaline cells scarcely convex on the outer surface, slightly so on the inner, up to one fourth of the diameter of the cell.
Dioicous. Antheridia in catkins on spreading branches; antheridial leaves brown, smaller than the normal branch-leaves, ovate with a sharp involute point, the hyaline cells shorter and wider. Fruiting branches erect; perichaetial leaves large, ovate, at the apex abruptly pointed with an involute often rent point, composed mostly of uniform narrow cells, the hyaline cells if differentiated reduced and without fibrils, showing membrane-gaps on the inner surface: capsule brown: spores brown-yellow, 20-25 m in diameter, granular-roughened.
Type locality: South Carolina.
Distribution: Labrador southward to Florida and Louisiana; Colorado; Washington to Alaska; also in South America, Europe, and Asia, and reported from Africa.

Sphagnum recurvum is a species of moss belonging to the family Sphagnaceae.

It is native to Eurasia and America.

Sphagnum recurvum là một loài rêu trong họ Sphagnaceae. Loài này được P. Beauv. mô tả khoa học đầu tiên năm 1805.