Bridel, Muscol. Recent., suppl. 1: 170. 1806.
to 100 × 3.5 mm wide.
usually profusely branched; axillary hyaline nodules present; central strand absent.
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
/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.
dioicous (?); perigonia not seen; perichaetia on short axillary branches in medial leaves.
theca slightly arcuate, bilaterally symmetric, astomatose, exothecial cells quadrate to oblong, vertical walls thicker than horizontal walls, 1.5-2 mm; peristome taxifolius-type.
Submerged in rapidly running water in calcareous sites; Alta., B.C., Ont.; Ala., Alaska, Ariz., Ark., Calif., Idaho, Ill., Ky., Mich., Mo., Mont., N.Y., Oreg., Tenn., Utah, Va., Wash., Wyo.; Mexico; Central America; Europe; Asia.
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
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:
(NICH) from Taiwan; and
(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."