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