Pleuridium Rabenh., Deutschl. Krypt.

Pleuridium Rabenh., Deutschl. Krypt. View in CoL -Fl. 2(3): 79. 1848.

Description (based on Russian collections [or with some features of species, which could be found in Russia and therefore included in the key to identification]. Plants small, in small loose tufts, green or yellow-green. Stems short, simple or weakly branched; central strand present [or, rarer, absent], rhizoids at stem bases, smooth. Leaves erect-spreading or erect, in proximal parts of stems distant, small, ovate to deltoid; becoming larger and crowd- ed near stem apex, from oblong or ovate base gradually or abruptly narrowed into subulate acumina filled by costa; margins plane, serrulate distally or subentire, all cells smooth, alar cells not differentiated; costa with one row

of guide cells, differentiated dorsal and ventral epidermal cells, dorsal stereid band of 1–2 cell layers, ventral stereid band of 0–1 cell layers; lamina unistratose or partially to completely bistratose at shoulders; cells short rectanular to elongate rectangular. Gonioautoicous or paroicous. Sporophytes usually single in perichaetia. Setae short. Capsules immersed, ovoid to almost spherical, with short beak, perfectly cleistocarpous [or with 2– 3 differentiated rows of annulus cells, and then the capsule dehiscence sometimes follows these rows]; stomata in lower part of urn [or in the middle]. Spores large. Calyptrae cucullate, smooth.