Toothed Sphagnum

This species is characterized among closely related species by its narrowly elongate branch leaves that are 4–6 times longer than wide.

Sporophytes are occasional, capsules mature in early to mid summer.

Distinguishing Sphagnum cuspidatum from S. viride is sometimes difficult, as both occur over a similar geographic range and both grow in wet carpets. Sphagnum cuspidatum has narrower branch leaves and usually a distinct red tinge at the branch bases within the capitulum.

Plants slender, soft, yellowish green to brown, somewhat shiny when dry. Stem cortex in 2–3 layers, hyaline cells large, thin-walled, without fibrils; central cylinder deeply yellowish green, clearly distinguished from the cortical cells. Stem leaves 1.2–2.0 mm × 0.5–0.8 mm, oblong-triangular to isosceles-triangular, gradually acute and slightly dentate at the apex, borders narrow above, clearly widened from the middle to the base (ca. 1/3 leaf base); hyaline cells narrow, undivided, often with fibrils, sometimes with small end pores on the dorsal surface. Branches in fascicles of 4, with 2 spreading. Branch leaves 2.0–4.0 mm × 0.5–0.6 mm, slightly shiny, often undulate at margins and secund when dry, narrowly ovate-lanceolate, gradually narrowed to a blunt, dentate apex; margins bordered by a few rows of linear cells; central hyaline cells narrowly elongate-rhomboidal, with small, ringed pores at the upper corners, rarely with pores at the lower corners on the dorsal surface, mostly with numerous small pores, rarely with rather large pores at the corners on the ventral surface, the inner walls adjacent to green cells smooth; the green cells in cross section trapezoidal, more broadly exposed on the dorsal surface. Dioicous; antheridial branches reddish brown; perigonial leaves shorter and wider than vegetative branch leaves. Perichaetial leaves broadly ovate with rounded apex, margins entire. Spores yellowish brown.

Plants slender and weak-stemmed, moderate-sized, flaccid and plumose in aquatic forms to more compact in emergent forms, spreading branches often con-spicuously falcate, giving capitulum a twisted appearance; green to yellow, often tinged with red, red-brown or brown in capitula. Stems green; superficial cortex of 2-3 layers, 2 layers of enlarged thin-walled cells. Stem leaves triangular-ovate, more than 1.2 mm, usually appressed; apex acute to apiculate, hyaline cells rarely septate or porose, apical region often fibrillose. Branches mostly unranked to weakly 5-ranked, often conspicuously falcate, leaves greatly elongated at distal end. Branch fascicles with 2 spreading and 2-3 pendent branches. Branch stems green, but often pinkish at the proximal ends, with cortex enlarged with conspicuous retort cells. Branch leaves ovate-lanceolate to lanceolate, 1.6-5 mm, falcate toward branch tips, when dry often undulate and recurved, rarely weakly serrulate along the margins in submerged forms, leaves from middle of spreading branches with length to width ratio less than or equal to 1:0.28; hyaline cells length to width ratio in apical convex surface region 8:1 or more, convex surface with 0-1 small round pores at apex, concave surface with faint round wall thinnings in cell apices and angles; chlorophyllous cells triangular to trapezoidal in transverse section, broadly exposed on the convex surface and exposed slightly on the concave surface. Sexual condition dioicous. Spores 29-38 µm; covered with large papillae on both surfaces, appearing pusticulate; proximal laesura less than 0.5 spore radius.

Distribution: China, India, Thailand, Indonesia, Malaysia, New Guinea, Australia, Europe, North, Central, and South America, and Africa.

Habitat: on wet humus under forests and bases of trees forming a hummock-hollow complex adjacent to bog mats.

Sphagnum cuspidatum var. plumosum Nees & Hornschuch; S. faxonii Warnstorf; S. virginianum Warnstorf