The Moss Families of the British Isles


L. Watson and M. J. Dallwitz


Plait-mosses, Feather-mosses, etc.

Excluding Amblystegiaceae, Brachytheciaceae, Entodontaceae, Sematophyllaceae, Plagiotheciaceae, Hylocomiaceae and Rhytidiaceae.

Gametophyte. Pleurocarpous; forming tufts, or mat or turf forming (or forming lax, coarse wefts). Primary stems erect to procumbent (the stems usually forked, often pinnately branched). Shoots complanate (often), or not complanate. Paraphyllia absent. Pseudoparaphyllia present (commonly), or absent. The leaves of main stems and branches similar in form to markedly different in form (the stem leaves nearly always larger, whether similar or different in form); ovate to lanceolate (or deltoid); spiral; secund, or not secund; longitudinally plicate, or not plicate. Leaf bases decurrent (e.g., Herzogiella, Ptilium), or not decurrent. The leaves nerveless, or double-nerved (very rarely single-nerved?). The leaf nerves when present, not extending beyond the middle of the leaf, or extending beyond the middle of the leaf, but not to the tip. Leaf blade apices pointed; apiculate, or not apiculate; apically rounded, or apically acute, or acuminate. Leaf blade margins usually at least distally denticulate, or dentate. Leaf blades not conspicuously bordered. The basal leaf cells somewhat longitudinally elongated to longitudinally much elongated; rounded to linear, or vermicular; smooth. The walls of basal leaf cells thin, or thick; straight. The angular cells usually clearly differentiated (sometimes enlarged or inflated, forming auricles). The mid-leaf cells longitudinally much elongated; rounded to linear, or vermicular; smooth. The walls of the mid-leaf cells thin, or thick; straight.

Plants monoecious, or dioecious; when monoecious, autoecious. Parapyhyses present among the reproductive organs, or absent.

Sporophyte. Capsules exserted; erect to horizontal; symmetrical to asymmetrical; straight to curved; sub-cylindric to ovoid; without an externally conspicuous apophysis; smooth; with an annulus. Calyptra symmetrical; splitting down one side. Capsules with a peristome. 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 usually well developed; shorter than the outer to exceeding the outer; with a basal membranous ring (this usually high); with elongated “processes” (these usually keeled). The processes of the inner peristome 16. The inner peristome ciliate. The cilia and processes of the endostome not united into a conical lattice. The cilia of the inner peristome usually nodulose or appendiculate. The operculum conical to mamillate, or rostellate to subulate. Setae long; usually curved; smooth (usually), or rough (then papillose).

Ecology. In wet places, or mesophytic, or xerophytic; occurring in basic habitats, neutral pH conditions, and acid conditions. In diverse habitats.

Cytology. Haploid chromosome number, n = 5, 6, 7, 8, 10, 11, 12, and 14.

British representation. About 35 species. Calliergonella (Spear- and Plait-mosses), Campylophyllum (Feather-mosses), Ctenidium (Comb-mosses), Herzogiella (Feather-mosses), Homomallium (Feather-moss), Hyocomium (Feather-moss), Hypnum (Plait-mosses), Isopterygiopsis (Silk-mosses), Platydicta (Leskea), Platygyrium (Flat-brocade Moss), Ptilium (Ostrich-plume Feather-moss), Pylaisia (Pylaisiella), Taxiphyllum (Depressed Feather-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 Bryideae; Order Hypnales.

Illustrations. • Ctenidium, Homomallium, Calliergonella, Hypnum spp., and Ptilium: Dixon. • Herzogiella, Isopterygiopsis and Taxiphyllum, with Plagiothecium: Dixon. • Pylaisia polyantha: Dixon. Pylaisia polyantha (Hedw.) Br. Eur. • Herzogiella striatella, with Plagiothecium spp.: Dixon. • 6 species of Amblystegium, and Conardia: Dixon. • Isopterygiopsis, Pseudotaxiphyllum and Pylaisia, with Plagiothecium and Homalothecium: Berkeley. • Hyocomium (Hypnaceae), with Hylocomiaceae: Berkeley. • "Hypnum revolvens" (with Campyliaceae, etc.: Berkeley. • Ctenidium, Hypnum and Ptilium (with Sematophyllum and Campyliaceae): Berkeley. • Campylophyllum (with Amblystegiaceae, Campyliaceae and Cratoneuron). • Calliergonella, with Campyliaceae. • Calliergonella, with Pleurozium and Pseudoscleropodium:: Berkeley.

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.’.