Pleuridium nitidum (Hedwig) Rabenhorst
Plants minute. Stems short, 0.4--2 mm, with innovations, central strand present. Stem leaves erect-spreading, lanceolate, to 1.8 mm at stem tip, base ovate, margins plane, entire, serrulate at the flat apex; costa thin and narrow, subpercurrent, with a central stereid band; laminal cells thin walled, smooth, 1-stratose, proximal cells larger and rectangular, distal cells rhombic. Seta 1--(2), short, erect. Capsule pale brown, 0.5--0.65 mm, ovoid with a short point, smooth, exothecial cells hyaline, quadrate, stomata only on proximal part of capsule. Calyptra 0.3--0.4 mm. Spores 22-28 µm, papillose, brown.
Capsules mature Nov. Damp soil, silt hummocks in grassy areas near river banks; B.C.; Oreg.; Mexico; South America; Europe; Africa (Congo; Kenya; Rwanda; Madagascar; Uganda; Zaire); Asia (Assam, Nepal, Japan); Australia (Tasmania); Pacific Islands (New Zealand).
This species is readily recognized by the lax and undifferentiated leaf cells, and the serrulate leaf tips. Vegetatively, it is superficially similar to Pohlia, Bryum, or Leptobryum species by the thin-walled laminal cells and the serrated leaf apices, but the rough papillose rhizoids of these genera distinguish them from Pseudephemerum nitidum. E. Nyholm (1986) reported asexual reproduction of P. nitidum by spherical gemmae. Pseudephemerum nitidum is newly reported from Oregon and Mexico from similar habitats (K. L. Yip 2002). The previous reports of this species in Canada could be verified only from a specimen from Richmond, British Columbia (Schofield 22437, UBC, WTU). A Nova Scotia report could not be confirmed after re-examination of the reported specimens (K. L. Yip 1998).
Matsui, T. & Z. Iwatsuki. 1990. A taxonomic revision of the family Ditrichaceae (Musci) of Japan, Korea and Taiwan. J. Hattori Bot. Lab. 68: 317--366.
Ochyra, R. 1995. The correct author citation for Pseudephemerum nitidum. J. Bryol. 18: 829.
Yip, K. L. 1998. The occurrence of Pseudephemerum nitidum (Hedw.) Loeske in North America, with some interesting observations. Evansia 15(3): 112--114.
Yip, K. L. 2002. Pseudephemerum, new to the United States and Mexico. The Bryologist 105: 256-258.