J. Hattori Bot. Lab. 33: 374. 1970. -- Leskea seligeri Brid., Musci Recent. 2(2): 47. 1865. -- Isopterygium seligeri (Brid.) Dix. ex C. Jens., Skand. Bladmfl. 489. 1939. -- Plagiothecium seligeri (Brid.) Lindb., Bot. Not. 1865: 144. 1865. -- Doklichotheca seligeri (Brid.) Loeske, Hedwigia 50: 244. 1911. --Sharpiella seligeri (Brid.) Iwats., J. Hattori Bot. Lab. 28: 203. 1965.
Plants in loose to dense mats, yellow-green to rather dark green, irregularly, often densely branched with branches and stems little different. Leafy axes similar wet or dry, to 3 cm long. Leaves loosely imbricated to approximate, to 2.5 mm, 3–4: 1, spreading and falcate, often homomallous, seldom complanate, lanceolate to ovate-lanceolate, gradually contracted from the decurrent base to the long acumen. Margins plane, narrowly decurrent, serrulate at least above the middle, serrate near apex. Median cells smooth, 4–7 µm wide, linear, up to 10: 1, thin walled, not pitted. At least a few cells at the alar angles somewhat enlarged and thin-walled, to 15 µm wide, not or inconspicuously decurrent; a single row of cells distal to these enlarged cells short rectangular and rather thick walled, thus sharply defining the boundary of the alar region. Median cells of leaf base linear to rectangular, 2–10: 1, rather thick walled and pitted. Costa inconspicuous, short and double. Pseudoparaphyllia wanting or abortive. Axillary hairs 4-celled, to 150 µm with a rather poorly differentiated basal brown cell, not offset from leaf insertion. Stem cross-section without a central strand, with a hyaloderm rather enlarged and thin walled compared to the adjacent several layers of small and brownish pachydermous cells, and with inner cortical cells enlarged with thin and hyaline walls. Rhizoids mostly abundant on prostrate axes, red-brown and finely papillose, sparingly branched, to 25 µm in diameter at insertion.
Autoicous with perigonia and perichaetia placed near one another in leaf axils on stoloniferous axes. Perichaetia somewhat shorter than the subtending leaves, with the bracts to 1.5 mm long, ovate below and loosely sheathing the seta, abruptly contracted near the apex into a short and narrow, serrulate acumen. Seta to 1.5 cm long, erect, brown to red-brown. Capsule yellow- to reddish-brown, cylindric and arcuate, often strongly so, sulcate to almost smooth, rather strangulate. Urn to 3.5 mm, 3–4: 1. Exothecial cells near mouth of capsule differentiated in 3–4 rows, dark-brown, isodiametric to somewhat transversely elongate with thick walls and round lumens, to 25 µm wide. Exothecial cells at mid urn irregular in size and shape, rectangular with oblique end walls, 1.5–6: 1, mostly in regular rows, not collenchymatous, to 25 µm broad. Stomata restricted to base of urn, cryptoporous. Annulus ill-defined, falling in fragments. Operculum conic to conic-apiculate, much shorter than urn. Exostome pale to yellow-brown, to 400 µm long, closely but often rather inconspicuously horizontally striate below, papillose above, with strong ventral trabeculae. Endostome segments papillose, perforate and keeled, about as long as exostome with basal membrane about 1/2 of total length. Cilia 1–3, mostly as long as the endostome processes, not nodose. Spores smooth to very lightly papillose, to 15 µm.