Robert R. Ireland
Stereodon sect. Plagiothecium (Schimper) Mitten
Plants dark green to yellow-green, glossy or sometimes dull. Stems 20--60 × 0.5--4 mm. Leaves 0.7--3 × 0.4--2 mm; median leaf cells 36--180 × 3--21 µm, apical cells often shorter, basal cells shorter and broader; decurrent alar regions triangular or often auriculate and oval in outline, consisting of 1--8 longitudinal rows of spherical, oval, quadrate, or rectangular cells. Specialized asexual reproduction present as smooth-walled propagula borne on stems and branches, 2--7-celled, uniseriate bodies. Sexual condition usually autoicous; perigonia and perichaetia numerous at bases of stems; perigonial bracts short, lanceolate to ovate, acuminate to filiform-acuminate; perichaetial leaves moderately enlarged, sheathing with somewhat spreading apices. Seta yellow, or orange to red-brown, Capsule yellow, or orange to red-brown, oblong to ovoid, often contracted under mouth when dry, smooth to striate, often wrinkled at neck; cilia 1--3, nodulose, as long as or nearly as long as the segments, rarely rudimentary or lacking.
Species ca. 80--90 (6 in the flora); North America, Central America, South America, Europe, Asia, Africa, Australia, Pacific Islands (New Guinea), Antarctic.
This is a genus of terrestrial habitats found in coniferous and deciduous woods, on rotten logs, stumps, bases of trees, humus and soil, frequently overlying acidic cliffs and boulders, sometimes in swamps and marshes, in temperate, boreal and Arctic regions, and at high elevations in the tropics.
SELECTED REFERENCES
Ireland, R. R. 1969. A taxonomic revision of the genus Plagiothecium for North America, north of Mexico. Natl. Mus. Canada, Natl. Mus. Nat. Sci., Publ. Bot. 1: 1--118. Ireland, R. R. 1986. Synopsis of the genus Plagiothecium for North America. Lindbergia 12: 49--56. Ireland, R. R. 1987. Scanning electron microscope study of the spores of the North American species of Plagiothecium. Mem. New York Bot. Gard. 45: 95--110.
OTHER REFERENCES
Hedenäs, L. 1989. Some neglected character distribution patterns among pleurocarpous mosses. Bryologist 92: 157--163.
Lin, S.-H. 1984. A taxonomic revision of Phyllogoniaceae (Bryopsida). Part II. J. Taiwan Museum 37(2): 1--54.
Ireland, R. R.. 1992. Studies of the genus Plagiothecium in Australasia. Bryologist 95: 221--224.
Ireland, R. R. 2001. Buckiella, a new genus in the Hypnaceae (Musci). Novon 11: 55--62.
McGrew, K. 1976. Bryophytes of the Russian Peak Area, Siskiyou County, California. M.A. Thesis, Humboldt State Univ., Arcata 62 pp.
Nyholm, E. 1965. Illustrated Moss Flora of Fennoscandia II. Musci. Fasc. 5. Plagiotheciaceae. Pp. 620--647. Lund.
Smith, A. J. E. 1978. The Moss Flora of Britain and Ireland. Plagiotheciaceae. Pp. 621--638. Cambridge.
