Fissidens Moss

Fissidens pauperculus is distinguished by its short costa, and smooth, plane laminal cells that gradually decrease in size outwardly. P. A. Florschütz (1964) equated specimens from Suriname with this species. R. A. Pursell (1994b) demonstrated, however, that the North American plants are different from those of South America. Although close to the South American plants that belong to F. inaequalis Mitten, the North American species differs by its slightly smaller laminal cells and in the absence of truncate-retuse vaginant laminae in the perichaetial leaves.

Plants 2-3 × 1.5-2.5 mm. Stems unbranched; axillary hyaline nodules absent; central strands weak. Leaves as many as 5 pairs, oblong to oblanceolate to lanceo-late, acute to short-acuminate, to 2.1 × 0.6 mm; margin crenulate-serrulate but often sharply serrate on distal parts of vaginant laminae, elimbate; dorsal lamina usually narrowed proximally, ending at insertion, not decurrent; vaginant laminae ± ¹/2-²/3 leaf length, unequal, minor lamina ending near margin; costa ending 6-15 cells before apex, bryoides-type; laminal cells 1-stratose, distinct, smooth, plane, firm-walled, long-hexagonal to oblong to regularly quadrate, decreasing in size from costa to margin, medial cells 10-54 × 12-25 µm, largest along costa, marginal cells 9-15 µm, juxtacostal cells in vaginant laminae pellucid, greatly enlarged. Sexual condition rhizautoicous and gonioautoicous. Sporophytes 1 per perichaetium. Seta 2.5-5 mm. Capsule theca exserted, usually inclined, slightly arcuate, bilaterally symmetric, infrequently erect, nearly radially symmetric, 0.7 mm; peristome scariosus-type; operculum 0.3-0.8 mm. Calyptra cucullate, smooth, 0.4 mm. Spores 9-13 µm.

Fissidens pauperculus M. A. Howe,
Er3rthea2:97. 1894.
Plants minute, loosely gregarious; stems decumbent or ascending, 1.5-2 mm. long in fertile plants; leaves 3-5 pairs, small below, increasing in size upwards, the upper and the perichaetial leaves nearly or quite 1 mm. long, acute to short-acuminate, the upper oblong to obliquely spatulate, subentire to irregularly crenulate above with projecting cell-angles, the border lacking, the costa stout, vanishing well below the apex; vaginant laminae unequal, one-third to one-half the length of the leaf; dorsal lamina not reaching the leaf-base in the upper leaves; upper leaf-cells irregularly hexagonal, smaller and rotmded toward the margin, larger and oblong-rectangular near the costa, those of the marginal row 7-10 jit in diameter, the others 9-16 X 16-40 fx; cells of the vaginant laminae narrower and longer along the margin near the base; dioicous; seta flexuous, pale, 3-5 mm. long; capsule ovoid to oblong-ovoid, inclined to cernuous, slightly arcuate when dry, the urn 0.5 mm. long, the exothecial cells oblong-rectangular, somewhat collenchymatous, shorter near the capsule mouth; operculum conic-rostellate, nearly equaling the urn in length; annulus pale, of 2-3 rows of cells; peristome normal, the prongs spirally thickened; spores 10-14 ju in diameter, in spring.
Type locality: Mill Valley, Marin Co., California, on soil of moist banks with F. Umbaius
{Howe) .
Distribution: Known only from the type locality.