Fissidens pellucidus Hornschuch 1841

The leaf shape of Fissidens pellucidus is variable. In the holotype the leaves are narrow with excurrent costa and the bases of dorsal laminae are wedge-shaped. However, in most Chinese specimens the leaves are broader mostly with percurrent costa (rarely excurrent) and the bases of the dorsal laminae always rounded. This species is closely allied to F. guangdongensis. The distinction between the two species is discussed under the latter.

Varieties 3 (1 in the flora): North America, Mexico, West Indies, Central America, South America, Asia, Africa.

Plants small, growing in loose tufts, usually brownish or reddish brown. Leafy stems simple, 2.4–5.2 mm long, 1.0–2.1 mm wide; axillary hyaline nodules lacking; central strand weakly differentiated. Leaves in 4–12 pairs, lower leaves very small, loosely arranged; upper leaves much larger than the lower leaves, densely arranged, lanceolate, 0.7–1.4 mm × 0.2–0.3 mm, acute to narrowly acute at apex; base of dorsal laminae wedge-shaped to rounded; vaginant laminae 1/2 the leaf length, unequal; costa stout, percurrent to shortly excurrent; margins crenulate to indistinctly serrulate; cells of apical and dorsal laminae quadrate to irregularly hexagonal, 10–24 µm long, thick-walled, transparent, smooth; cells of upper half of vaginant laminae similar to those of apical and dorsal laminae, but narrower toward the base. Polyoicous. Perichaetial leaves differentiated, upper end of vaginant laminae rounded, open to costa, cells at upper end of vaginant laminae elongate, irregularly rhombic, thick-walled. Archegonia 245–390 µm long. Setae 2.5–2.9 mm long, smooth; capsules erect, symmetrical; urns ovoid, 0.4–0.5 mm long; exothecial cells quadrate to broadly oblong, thin-walled with distinctly thickened corners, distinctly mammillose; opercula conic-rostrate, ca. 0.4 mm long; peristome teeth 0.28 mm long, 36 µm wide at base, spirally thickened above, densely covered by minute papillae below.

Distribution: China, Japan, Nepal, India, Sri Lanka, Myanmar, Thailand, Vietnam, Malaysia, Singapore, Indonesia, the Philippines, and South America.

Habitat: on soil.

Fissidens crassinervis Thwait. & Mitt., J. Linn. Soc. Bot. 13: 323. 1873, hom. illeg., non Fissidens crassinervis Sande-Lac., Verh. Kon. Ned. Akad. Wetensch., Afd. Natuurk. 13: 3. Pl. 2: a.1872. Fissidens laxus Sull. & Lesq., Proc. Amer. Acad. Arts Sci. 4: 275. 1859. Type. China: Hong Kong, C. Wright s.n. (holotype FH). Fissidens mittenii Par., Ind. Bryol. 477. 1894.

Fissidens pellucidus Hornsch I^innaea 15: 146. 1841.
Conomitrium pellucidum C. Miill. Syn. 2: 525. 1851
Conomiirium asterodoniium C. Mull. Syn. 2: 527. 1851.
Fissidens subcrenatus Schimp.; C. Mtill. Syn 2: 531. 1851.
Fissidens rufulus Sull. Proc. Am. Acad. 5: 275. 1861. Not F. rufulus B.S.G. 1851.
Fissidens Wrightii Jaeger, Enum. Fissid. 12. 1869.
Fissidens asterodontium Mitt. Jour. Linn. Soc. 12: 5»7. 18oy.
Fissidens pyrenocystis Card. Rev. Bryol. 37: 121. 1910.
Plants annual, scattered or gregarious, usually of the same color as the red earth on which they grow; stems simple, without mnovations, either erect or decumbent, from 2-3 mm. up to 5 mm. high (seldom more), stout and rufescent or ferruginous; leaves reflexed when dry, 3-8 pairs, up to 12 pairs on sterile stems, not crowded nor overlapping, increasing m size upward to 1.5 X 0.33 mm., oblong-lanceolate, acute to obtuse and usuaUy entire, or crenateserrulate but not bordered, the costa stout, brown, ending plainly below the apex (with few exceptions), from 27-40 m wide, bent and somewhat flexuous above the middle; apical lamina with only 8-12 rows of cells between vein and margin, the cells smooth, pellucid, slightly tumid, hexagonal with thick brown walls, up to 24 ^ in diameter, the marginal cells smaller, up to 16 Ml transversely elongate and oblong; vaginant laminae about half the length of the leaf, usually unequal, with one blade narrower than the other and ending at or near the costa at the apical junction, the cells not much larger than in the apical lamina, a few somewhat elongate next the costa at the base ; dorsal lamina tapering to the base or ending abruptly ; perichaetial leaves connivent, with the vaginant laminae unequally enlarged; dioicous or synoicous (?), the autheridia and archegonia terminal, usually on smaller plants with fewer leaves; seta bent at base, becoming erect, 2-5 mm. long; capsule up to 1 mm. long, the urn ovoid or cylindric, contracted below the mouth when dry, the base of the operculum and the upper walls of the urn of thickened collenchyma cells, often black around the mouth; calyptra short, covering only the long beak of the operculum; annulus falling with the operculum; peristome exserted on a short membrane, spreading when dry, strongly inroUed when moist, the teeth spirally thickened at apex; spores smooth, yellow, up to lO/x in diameter, maturing after the rainy season
Type i,ocality:
Distribution: Southern North America (Georgia, Harper 1615b) to Brazil; apparently common in the West Indies.