The Moss Families of the British Isles
Gametophyte. Pleurocarpous; dendroid (the secondary stems growing erect like tiny trees, with homomallous branches above); forming tufts, or forming patches. Primary stems procumbent (stoloniform). Mature plants 15–200 mm high. Shoots complanate to not complanate, or not complanate. Stems with a differentiated central strand. The leaves of main stems and branches markedly different in form; on the stems deltoid, on the branches ovate to lanceolate; spiral; single-nerved. The leaf nerves extending beyond the middle of the leaf, but not to the tip. Leaf blade apices pointed; not apiculate; apically acute, or acuminate. Leaf blade margins flat; distally denticulate (in branch leaves), or entire (in stem leaves). Leaf blades not conspicuously bordered. The basal leaf cells more or less isodiametric to somewhat longitudinally elongated; papillose. The walls of basal leaf cells thick; straight. The angular cells not well differentiated. The mid-leaf cells somewhat longitudinally elongated (in stem leaves), or more or less isodiametric to somewhat longitudinally elongated (in branch leaves); quadrate, or rounded (rounded to sub-quadrate in branch leaves, shortly elliptic in stem leaves); papillose. The walls of the mid-leaf cells thick; straight.
Sporophyte. Capsules exserted; inclined; symmetrical to asymmetrical; curved; ellipsoid, or ovoid; without an externally conspicuous apophysis; with an annulus. Calyptra large and covering the well-developed capsule; glabrous, or hairy; symmetrical; splitting down one side. Capsules dehiscing via a lid; with a peristome (pale red). The peristome double. The peristome teeth 16; not grouped; not deeply cleft; not perforated; thin, membranous, and transversely barred; exteriorly with a fine longitudinal dividing line between the transverse bars. The inner peristome well developed; shorter than the outer to about equalling the outer; with a basal membranous ring (this wide); with elongated processes. The processes of the inner peristome 16. The inner peristome ciliate (with three appendicular cilia between adjacent processes). The operculum strongly rostrate, or subulate (oblique). Setae about 1–1.5 cm long; distally curved.
Ecology. The common T. alopecurum on moist, shaded rocks, tree roots and trunks in and by streams and in damp places, rarely on dry rocks. Apart from a doubtful record for Antrim, T. angustifolium is recorded in Britain only from Derbyshire, on damp, vertical, shaded limetone.
Cytology. Haploid chromosome number, n = 11.
British representation. 3 species. Thamnobryum (Thamnium); Feather-mosses. Northern Scotland, southern Scotland, northern England, English Midlands, East Anglia, Wales, southeast England, central southern England, southwest England, Isle of Wight, and Ireland.
Classification. Class Bryopsida; Subclass Bryideae; Order Hypnales.
Comments. Returned to Neckeraceae in recent treatments.
Illustrations. • Thamnobryum alopecurum and T. angustifolium: Dixon. • Thamnobryum alopecurum: Berkeley. • Thamnobryum alopecurum: Curtis (1826).
To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2005 onwards. The moss families of the British Isles. Version: 21st June 2009. http://delta-intkey.com’.