The moss families (Bryophyta, Musci) of Britain and Ireland

L. Watson and M.J. Dallwitz

Dicranaceae

Swan-neck Mosses, Bow-mosses, Fork-mosses, etc.

Excluding Ditrichaceae, Seligeriaceae, Leucobryaceae and Rhabdoweisiaceae

Gametophyte. Acrocarpous (usually), or pleurocarpous (e.g., Dicranum scoparium); forming tufts, or mat or turf forming, or forming patches, or growing through other Bryophytes. Mature plants when erect or ascending, 2–150 mm high. Stems tomentose below (commonly, e.g. in Dicranum, and Campylopus often with red or red-brown tomentum), or not tomentose; with a differentiated central strand. The leaves neither sphagnoid nor leucobryoid. The leaves ovate, or lanceolate to narrowly lanceolate (commonly), or linear to subulate; not distichous; spiral; secund (or falcato-secund), or not secund; tightly to loosely crisped when dry, or not crisped when dry; single-nerved. The leaf nerves extending beyond the middle of the leaf, but not to the tip to extending to the leaf tip; excurrent to not excurrent (sometimes percurrent); incorporating stereids. Leaf blade apices conspicuously hyaline (3 Campylopus spp.), or not hyaline. Leaf blade margins unistratose, or bi-stratose. The basal leaf cells somewhat longitudinally elongated to longitudinally much elongated; rectangular to linear; smooth. The angular cells clearly differentiated (mostly, sometimes forming auricles), or not well differentiated (Dicranelloideae). The mid-leaf cells more or less isodiametric to longitudinally much elongated; quadrate to linear; smooth.

Plants monoecious, or dioecious (commonly); when monoecious, autoecious, or paroecious.

Sporophyte. Capsules exserted; erect, or inclined; symmetrical, or asymmetrical; straight, or curved; sub-cylindric, or ovoid, or pyriform (rarely), or gibbous; with an externally conspicuous apophysis (occasionally), or without an externally conspicuous apophysis (mostly); smooth (in Dicranum, etc.), or striate and becoming regularly furrowed when dry and empty (commonly, in some genera); with an annulus, or without an annulus; dehiscing via a lid; with a peristome. The peristome single. The peristome teeth 16 (usually), or 32 (if divided to the base); not grouped; deeply cleft (often almost to the base, into 32 divisions); not perforated, or perforated; thin, membranous, and transversely barred (and transversely articulated); usually interiorly exhibiting a fine longitudinal dividing line between the transverse bars (if not divided to the base); flat, papillose above and vertically striate-pitted below. The operculum rostellate to subulate. Setae usually long; curved, or straight.

Cytology. Haploid chromosome number, n = 7, 10, 11, 12, 13, 14, 15, 22, and 23 (sometimes with one or 2–3 supernumeraries).

Representation in Britain and Ireland. About 46 species. Aongstroemia (Sprig-moss), Arctoa (Fork-moss), Campylopus (Swan-neck Mosses), Dicranodontium Bow-mosses), Dicranella (Forklet-mosses), Dicranum (Fork-mosses), Kiaeria (Fork-mosses), Paraleucobryum (Long-leaved Fork-moss). 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 Dicranideae; Order Dicranales.

Comments. The leaves usually more or less uniform in size up the stems.

Illustrations. • Dicranella (with Rhabdoweisiaceae and Trematodon): Dixon. DICRANACEAE: H, Dicranella heteromalla (Hedw.) Schimp. I, D. cerviculata (Hedw.) Schimp. J, D. crispa (Hedw.) Schimp. K, D. subulata (Hedw.) Schimp. RHABDOWEISIACEAE: A, Cynodontium jenneri (Pöch) Limpr. B, C. gracilascens (Web. & Mohr.) Schimp. (probably a spurious record for Britain and/or Ireland). C, Onchophorus virens (Hedw.) Brid. D, Onchophorus wahlenbergii Brid. E, Dichodontium pellucidum (Hedw.) Schimp. F, Dichodontium flavescens (With.) Lindb. BRUCHIACEAE: G, Trematodon ambiguus (Hedw.) Hornsch.

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. • Campylopus and Dicranella, with Rhabdoweisiaceae and Blindia: Dixon. DICRANACEAE: A, Dicranella subulata (Hedw.) Schimp.; B, Dicranella rufescens (With.) Schimp.; C, Dicranella varia (Hedw.) Schimp.; D, Dicranella grevilleana (Brid.) Schimp.; E, Dicranella schreberana (Hedw.) Dix. K, Campylopus subulatus Schimp.; L, Campylopus schimperi Milde. RHABDOWEISIACEAE: F, Dichodontium palustris (Dicks.) M. Stech. I, Dicronoweisia cirrata (Hedw.) Lindb. ex Milde; J, Dicranoweisia crispula (Hedw.) Milde; SELIGERIACEAE: G, Blindia caespiticium (Web. & Mohr) C. Müll.; H, Blindia acuta (Hedw.) Br. Eur.

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. • Arctoa, Campylopus, Dicranum, Dicranodontium and Kiaeria. DICRANACEAE: A, Campylopus introflexus (Hedw.) Brid.; B, Campylopus brevipilus Br. Eur.; C, Dicranodontium denudatum (Brid.) Britton & Williams; D, Arctoa fulvella (Dicks.) Br. Eur.; E, Kiaeria falcata (Hedw.) Hagen; F, Kiaeria blyttii (Schimp.) Broth.; G, Kiaeria starkei (Web. & Mohr) Hagen; H, Kiaeria glacialis (Berggr) I. Hagen.; I, Dicranum polysetum Sw.

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. • Arctoa, Campylopus, Dicranum and Dicranella: Berkeley. DICRANACEAE: 4, Campylopus flexuosus (Hedw.) Brid.; a, habit; b, leaf; c, calyptra; d, capsule. 7, Dicranum scoparium Hedw.; a, habit; b, leaf; c, part of peristome. 8, Dicranella heteromalla (Hedw.) Schimp.; a, habit; b, leaf; c, capsule; d, part of peristome. 10, Arctoa fulvella (Dicks.) R. Br.; a, habit; b, leaf; c, capsule; d, part of peristome. DITRICHACEAE: 5, Ceratodon purpureus (Hedw.) Brid.; a, habit; b, leaf, c, capsule; d, part of peristome; e, detail of peristome tooth tip. RHABDOWEISIACEAE: 9, Oreoweisia bruntonii (Sm.) Milde; a, habit; b, leaf; c, capsule; d, part of peristome. LEUCOBRYACEAE: 6, Leucobryum glaucum (Hedw.) Ångstr.; a, habit; b, leaf; c, leaf tip; d, capsule; e, part of peristome.

From Berkeley (1863, Plate 23). The approximate 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’.

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