Largeleaf Fissidens Moss

Fissidens grandifrons is the only species in the flora area with pluristratose laminal cells. It is a robust aquatic species, usually coarse to the touch. The plants are often brown-black, the result of deposition of organic matter. Reproduction in North America, where sporophytes have never been found, is by vegetative means. According to E. J. Hill (1902), multiplication is by small, radiculose branches that are easily detached in the rapidly running streams. Although the gametophyte of F. grandifrons is specialized to an aquatic habitat (thick, lanceolate leaves and long archegonia; Z. Iwatsuki and T. Suzuki 1982; R. A. Pursell and B. H. Allen 1994), the species has retained a distinctly terrestrial type of sporophyte. The description of the sporophyte given here is based on three specimens: Lai 8699 (NY) and Lin 12831 (NICH) from Taiwan; and Higuchi 20161 (NICH) from Pakistan. A. J. Grout (1943) stated that the operculum is “conic-rostrate, about 1 mm long,” and Iwatsuki and Suzuki reported that the calyptra is “cucullate, about 1.6 mm long, smooth.”

Plants medium-sized to large, creeping, dark green, rigid, brownish when old. Leafy stems simple or branched, 16–86 mm long, 2.5–3.0 mm wide; axillary hyaline nodules differentiated; cortical cells small, thick-walled; central strand not differentiated. Leaves in 13–83 pairs, densely arranged, stiff even when dry, the lowest leaves small, middle to upper leaves lanceolate to ensiform-lanceolate, 2.8–3.5 mm × 0.4–0.5 mm, obtuse to acute at apex; base of dorsal laminae wedge-shaped, decurrent; vaginant laminae about 1/2 the leaf length, equal; costa stout, but obscure, ending a few cells below leaf apex; margins slightly serrulate; in cross section apical and dorsal laminae 1–2 cells thick at margin, 3–6 cells thick near costa, one cell thick for most parts of vaginant laminae; laminal cells near margin smaller, with thinner cell walls, larger, with thicker cell walls toward costa; cells of apical and dorsal laminae quadrate to hexagonal, 7–11 µm long, smooth, moderately thick-walled to thick-walled; cells of vaginant laminae similar to those of apical and dorsal laminae, but larger, with thicker walls toward base. Dioicous. Female inflorescences axillary. Archegonia 400–640 µm long, with stalks up to 140 µm long. Setae 18–21 µm long, smooth; capsules erect to horizontal, symmetrical; urns cylindric, 1.1–1.6 mm long; exothecial cells quadrate to shortly rectangular; peristome teeth ca. 0.43 mm long, 114 µm wide at base. Spores 14–25 µm in diameter.

Plants to 100 × 3.5 mm wide. Stem usually profusely branched; axillary hyaline nodules present; central strand absent. Leaves in as many as 60 or more pairs, lanceolate, obtuse to rounded, to 3 × 0.5 mm; dorsal lamina narrowed proximally, ending at insertion; vaginant laminae ¹/2-²/3 leaf length, acute, equal; margin ± entire to crenulate, elimbate; costa usually difficult to discern, ending a few cells before apex, variable in structure, basically taxifolius-type; lamina cells 1- to 4-stratose at leaf margin, 2- to pluristratose in interior of dorsal and ventral laminae, 1- to 4-stratose in vaginant laminae, smooth, ± plain, quadrate to hexagonal, 7-13 µm long. Sexual condition dioicous (?); perigonia not seen; perichaetia on short axillary branches in medial leaves. Seta 13-19 mm. Capsule theca slightly arcuate, bilaterally symmetric, astomatose, exothecial cells quadrate to oblong, vertical walls thicker than horizontal walls, 1.5-2 mm; peristome taxifolius-type. Spores 20-23 µm.

Distribution: China, Korea, Japan, Nepal, India, North and Central Africa, and North and Central America.

Habitat: on wet or submerged rocks.

Fissidens diversiretis Broth., Symb. Sin. 4: 11. 1929. Type. China: Yunnan, between Ngaiwa and Mekong, 7 X 1915, Handel-Mazzetti 8477 (holotype H-BR). Fissidens grandifrons var. planicaulis (Besch.) Nog., J. Hattori Bot. Lab. 7: 68. 1952. Fissidens planicaulis Besch., Ann. Sci. Nat. Bot., sér. 7, 17: 335. 1893. Fissidens yunnanensis Besch., Rev. Bryol. 18: 88. 1891. Type. China: Yunnan, Delavay 4631 (isotype H-BR).

Pachyfissidens grandifrons (Bridel) Limpricht