Fissidens berteroi

Detailed description

Plants very large for the genus, on rock, wood, or concrete, submerged in flowing water, bright green; shoots soft, flexuous, forming tufts or mats, to 10 cm long, 10 mm wide, frequently branched; rhizoids at stem base, occasionally in leaf axils, and in one gathering copious on the distal part of the leaf lamina and there subtending plantlets; stems without central strand, axillary hyaline nodules weakly differentiated; leaves in many pairs, patent, distant, flaccid, shrunken when dry, 5-9 mm long, 0.5-0.9 mm wide; leaf apex acuminate; vaginant lamina 2/5-1/2 of leaf length, joined to near leaf margin; dorsal lamina 25- 35 cells wide opposite junction of vaginant lamina, failing before insertion; nerve green, indistinct, failing 15-40 cells before leaf apex, 45-60 microns wide at junction of vaginant lamina, tapering from there to nerve apex, in cross-section all cells thin-walled; leaf margins entire with occasional serrations, especially near leaf apex, unbordered except sometimes a very weak border on margin of lower third of vaginant lamina; laminae unistratose, cells of apical and dorsal lamina 5-6 sided in face view, thin-walled, smooth, increasing greatly in size from margin to nerve, (10-) 15-18(-22) x 9-12 microns in mid-lamina; cells of vaginant lamina similar. Paroicous. Perichaetia and perigonia adjacent in leaf axils, on very short shoots, with reduced leaves; setae 0.8-1.5 mm long; capsule cupulate, urn 0.8 mm long, exothecial cells c. 80 around perimeter; operculum with a very short, blunt, slightly oblique beak, less than ½ the length of the urn; peristome teeth short, 200-245 microns long, 50-70 microns wide at base, scarcely covering capsule mouth when moist, irregularly bifid for 2/3 or more of their length, some lacunate to near base, lamellae finely papillose on dorsal surface of tooth, variably so on ventral, prongs with oblique ridges, tips truncate or tapering; spores (16-)18-22(-25) microns, papillose; calyptra cucullate.