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| The moss families (Bryophyta, Musci) of Britain and Ireland |
Thamnobryaceae; ~Neckeraceae
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.
Plants dioecious.
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.
Representation in Britain and Ireland. 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. THAMNIACEAE: B, Thamnobryum alopecurum (Hedw.) Dix.; C, Thamnobryum angustifolium (Holt) Crundw.
From Dixon and Jameson (1924), the unscaled screen display approximately doubling the magnifications given with their individual figures. 1, leaf or stem leaf where these differ; 2, branch-leaf; 3, perichaetial leaf; 4, perigonial leaf; 5, capsule; 6, peristome; 7, calyptra; 8, spores; 9, inflorescence; 10, gemmae; 11, paraphyllia; 12, stoma of capsule; *, plant, or part of one. Qualifications: a, apex; b, base; c, cells at one third from the apex; cv, ventral aspect of cells; cd, dorsal aspect of cells; bc, basal cells; x, section. • Thamnobryum alopecurum: Berkeley. THAMNIACEAE: Thamnobryum alopecurum (Hedw.) Nieuwl.; a, leaf; b, calyptra; c, capsule.
From Berkeley (1863, Plate 13). The approximate 1 cm scale applies to the whole plant (habit) illustration only. • Thamnobryum alopecurum: Curtis (1826).
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, 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. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2005 onwards. The moss families (Bryophyta, Musci) of Britain and Ireland. Version: 5th August 2019. delta-intkey.com’.
