The Moss Families of the British Isles


L. Watson and M. J. Dallwitz


Spear-mosses, Feather-mosses, Hook-mosses, etc.


Gametophyte. Pleurocarpous; not dendroid; forming tufts, or mat or turf forming, or forming patches. Shoots not complanate. Paraphyllia mostly absent. Pseudoparaphyllia absent (at least, never mentioned). Stems tomentose below, or not tomentose. The leaves of main stems and branches similar in form (though the branch leaves are often smaller); bilaterally symmetrical; mostly ovate to narrowly lanceolate (or deltoid); spiral; commonly sub- or falcato- secund, or secund, or not secund; more or less longitudinally plicate (e.g., Campylium stellatum, Drepanocladus spp.), or not plicate (mostly). Leaf bases somewhat decurrent (e.g., in Campylium), or not decurrent. The leaves nerveless, or double-nerved, or single-nerved. The leaf nerves when present, extending beyond the middle of the leaf, but not to the tip (commonly to about half-way), or not extending beyond the middle of the leaf to extending beyond the middle of the leaf, but not to the tip (e.g., in Hygrohypnum), or extending to the leaf tip; not excurrent (mostly), or excurrent (sometimes, in Drepanocladus). Leaf blade apices pointed (nearly always); apically acute, or acuminate. Leaf blade margins flat; unistratose; entire, or entire to denticulate, or denticulate. Leaf blades not conspicuously bordered. The basal leaf cells longitudinally much elongated (mostly), or somewhat longitudinally elongated; rounded to rhomboidal, or linear to vermicular; smooth. The walls of basal leaf cells thin, or thick; straight. The angular cells clearly differentiated (frequently), or not well differentiated. The mid-leaf cells longitudinally much elongated (mostly), or somewhat longitudinally elongated to longitudinally much elongated; narrowly or irregularly rectangular, or hexagonal, or linear, or vermicular; smooth. The walls of the mid-leaf cells thin, or thick; straight.

Plants monoecious, or dioecious; when monoecious, autoecious.

Sporophyte. Capsules exserted; inclined, or horizontal; at least somewhat somewhat asymmetrical; curved; sub-cylindric to ellipsoid (often somewhat contracted below the mouth after dehiscence), or gibbous (sometimes somewhat, e.g. in Campylium elodes); with an externally conspicuous apophysis (only occasionally), or without an externally conspicuous apophysis; smooth; mostly with an annulus. Calyptra glabrous; 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 (often distinctly articulated); exteriorly with a fine longitudinal dividing line between the transverse bars. The inner peristome well developed; shorter than the outer to exceeding the outer (?); with a basal membranous ring; with elongated “processes” (these broad). The processes of the inner peristome 16; alternating with the teeth of the outer peristome. The inner peristome ciliate. The cilia of the inner peristome entire. The operculum shortly conical, or conical and mamillate. Setae long; usually curved (?); reddish; smooth.

Ecology. Aquatic, or in wet places (mostly), or mesophytic; occurring in basic habitats (commonly), or neutral pH conditions, or acid conditions. Mostly found in moist, wet or aquatic habitats - especially fens, marshes, dune slacks, basic flushes, etc., occasionally on damp rocks.

Cytology. Haploid chromosome number, n = 8, 9, 10, 11, 12, 18, 20, 22, and 24 (occasionally with supernumeraries).

British representation. 32 species. Calliergon (Spear-mosses), Campylium (Starry Feather-mosses), Campyliadelphus (Feather-mosses), Conardia (Compact Feather-moss), Drepanocladus (Hook-mosses), Hamatocaulis (Varnished Hook-moss), Hygrohypnum (Brook-mosses), Pictus (Pict-moss), Pseudocalliergon (Hook-, Spear-, and Scorpion-mosses), Sanionia (Hook-mosses), Scorpidium (Hook- and Scorpion-mosses), Straminergon (Straw Spear-moss), Tomentypnum (Woolly Feather-moss), Warnstorfia (Hook-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.

Illustrations. • Hygrohypnum, Straminergon. Scorpidium, Caliergon and Warnstorfia, with Calliergonella): Dixon. • Campylium, Campyliadelphus and Drepanocladus (with Amblystegiaceae, Cratoneuron and Campylophyllym): Dixon. • 6 genera (with Palustriella): Dixon. • Hygrohypnum, Straminergon, Scorpidium and Warnstorfia (with Calliergonella): Dixon. • Campylium, Campyliadelphus and Drepanocladus (with Amblysegiaceae and Rhyncostegium): Berkeley. • Calliergon, Hygrohypnum and Straminergon: Berkeley. • Drepanocladus and Sanionia (with Cratoneuron, Palustriella and Rhytidiadelphus): Berkeley. • Drepanocladus and Scorpidium (with Hypnaceae and Sematophyllum): Berkeley. • Tomentypnum, with Ptychodium, with Brachytheciaceae and Orthothecium: Dixon. • Conardia, with Amblystegium spp.: Dixon. • Hygrohypnum luridum, with Hypnaceae: Dixon.

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.’.