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| The moss families (Bryophyta, Musci) of Britain and Ireland |
Hoar-mosses.
In Dixon’s Grimmiaceae
Gametophyte. Pleurocarpous (with irregular branching); forming tufts, or forming patches (yellowish- or glaucous-green). Stems without a differentiated central strand. The leaves oblong to ovate, or ovate to lanceolate (concave); spiral; sometimes (falcato-) secund, or not secund; nerveless. Leaf blade apices pointed; apically acute to acuminate; conspicuously hyaline (H. ciliata), or not hyaline. Leaf blade margins at least proximally revolute or recurved. Leaf blades bordered to not conspicuously bordered. The basal leaf cells longitudinally much elongated; narrowly rectangular, or linear; papillose. The walls of basal leaf cells thick; sinuous. The angular cells clearly differentiated (the cells rectangular to transversely so). The mid-leaf cells somewhat longitudinally elongated; quadrate, or rectangular, or rhomboidal; papillose (the papillae simple or branched). The walls of the mid-leaf cells thick; sinuous.
Plants monoecious; autoecious.
Sporophyte. Capsules immersed to emergent, or exserted (but no more than shortly exserted); erect; symmetrical; if more or less elongated, straight; shortly sub-cylindric (obloid), or pyriform; with an externally conspicuous apophysis to without an externally conspicuous apophysis. Calyptra fugacious, small; symmetrical; not plicate; splitting down one side. Capsules without a peristome. The operculum conical. Setae very short; straight.
Ecology. Xerophytic; occurring in acid conditions. On dry, exposed, siliceous rocks, walls and roofing slates, at low to moderate altitudes.
Cytology. Haploid chromosome number, n = 10 (or 10 + 1), or 11, or 21, or 22.
Representation in Britain and Ireland. 3 species. Hedwigia. 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 Hedwigiales.
Illustrations. • Hedwigia ciliata and Hedwigia integrifolia. HEDWIGIACEAE: A, Hedwigia ciliata (Hedw.) P. Beauv.; B, Hedwigia integrifolia P. Beauv.
From Dixon (1924), the unscaled screen display approximately doubling the magnifications given with his 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. Hedwigia ciliata. H. integrifolia. • Hedwigia, with Grimmiaceae and Ptychomitriaceae: Berkeley. HEDWIGIACEAE: 7, Hedwigia integrifolia P. Beauv; a, habit; b, leaf; c, capsule. 8, Hedwigia ciliata (Hedw.) P. Beauv.; a, habit; b, leaves; c, detail of leaf tip; d, capsule. PTYCHOMITRIACEAE: 1, Ptychomitrium polyphyllum (Sw.) Br. Eur.; a, habit; b, leaf; c, capsule; d, part of peristome. 2, Glyphomitrium daviesii (With.) Brid.; a, habit; b, leaf; c, calyptra (but this usually plicate); d, capsule; e, part of peristome. GRIMMIACEAE: 3, Racomitrium aciculare (Hedw.) Brid.; a, habit; b, leaves; c, capsule; d, part of peristome; d, detail of tip of a peristome tooth. 4, Racomitrium heterostichum (Hedw.) Brid.; a, habit; b, leaf; c, capsule; d, part of peristome. 5, Grimmia pulvinata (Hedw.) Smith; a, habit; b, leaf; c, capsule; d, part of peristome, and detail of the annulus. 6, Schistidium apocarpum (Hedw.) Br. Eur.; a, habit; b, leaves; c, capsule; d, part of peristome; e, columella, with the lid attached.
From Berkeley (1863, Plate 21). The 1 cm scale applies to the whole plant (habit) illustrations only.
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’.
