Fissidens minutulus

Fissidens minutulus SuU. Mem. Am. Acad
11. 3: 58. 1848.
Fissidens viridulus var. pusillus Wils. Bryol. Brit. 303. 1855. Fissidens incurvus var. pusillus Schimp. Syn. 104. 1860. Fissidens pusillus Wils. in Milde, Bryol. Siles. 82. 1869. Fissidens pusillus var. madidus Spruce, Jour. Bot. 18: 361. 1880.
Plants very small, 1-3 mm. long, 5 mm. at the utmost; lower leaves small and in young plants often scarcely margined, the upper, especially the perichaetial, narrowly lanceolate, often somewhat curved, 0.24-0.3 X 1-1.2 mm., the stem leaves at most 0.45 mm. wide, usually in 3-4 pairs, occasionally, more, acute, often apictdate, the border mostly ending below the apex and the apical margin usually somewhat irregular to faintly serrulate, the costa percurrent in the upper leaves; vaginant laminae about half the length of the leaf, the sides often unequal; dorsal lamina narrowed at base and reaching the stem in the upper leaves only, as a rule; leaf-cells irregularly quadrate to rectangular-hexagonal, about 10 m in diameter but varying greatly in size and shape, some reaching 15 /x in longest dimension, those of the vaginant laminae near the costa often elongated to 22 /xJ mostly dioicous; seta 3-4 mm. long; capside erect or inclined, strongly contracted below the mouth when dry and empty, obovoid, the urn reaching 0.7 mm. in length but usually shorter, the operculum conic-apiculate to rostrate, often nearly as long as the urn, the exothecial cells quadrate to roimded-hexagonal above, rectangular below with rounded corners, collenchymatous, the longitudinal walls much thicker than the transverse; peristome-teeth deep red, deeply cleft, very rough and subspirally thickened with rather obscure markings; spores about 15 ju in diameter, ripening from August to September (occasionally as late as November at Washington, D. C).
Type i/)Cality: Northeastern United States.
Distribution: Common on wet rocks in cool shaded places, occasionally on moist banks, rarely on limestone; eastern Canada and the United States south to the Gulf of Mexico; occasionally west
of the Rocky Mountains.