The Moss Families of the British Isles


L. Watson and M. J. Dallwitz


Excluding Thamniobryum, Habrodon and Helicodontium.

Gametophyte. Pleurocarpous; forming patches, or forming wefts. Primary stems procumbent (stoloniform, rarely rhizomatous). Shoots not complanate. Stems with a differentiated central strand (but only an ill defined one), or without a differentiated central strand. The leaves broadly ovate to lanceolate (often plicate); spiral; longitudinally plicate (Antitrichia, Leucodon), or not plicate (Pterogonium); nerveless (Leucodon), or single-nerved. The leaf nerves when present, not extending beyond the middle of the leaf (Pterogonium), or extending beyond the middle of the leaf, but not to the tip (Antitrichia). Leaf blade apices pointed; apiculate, or not apiculate; apically acute, or acuminate. Leaf blade margins flat, or revolute or recurved; distally denticulate, or dentate, or entire. Leaf blades bordered to not conspicuously bordered. The basal leaf cells longitudinally much elongated; smooth. The walls of basal leaf cells thick; straight. The angular cells clearly differentiated. The mid-leaf cells more or less isodiametric to somewhat longitudinally elongated, or longitudinally much elongated. The marginal mid-leaf cells not more than twice as long as wide (supposedly distinguishing from Entodontaceae). The mid-leaf cells rounded to rhomboidal, or linear to vermicular; smooth. The walls of the mid-leaf cells thick; straight.

Plants dioecious.

Sporophyte. Capsules exserted; erect, or inclined; symmetrical, or symmetrical to asymmetrical; slightly curved, or straight; sub-cylindric, or ellipsoid, or ovoid; without an externally conspicuous apophysis; with an annulus to without an annulus (when present, narrow or weakly differentiated). Calyptra symmetrical; splitting down one side. Capsules with a peristome. The peristome single to double (the teeth being irregular, short and fugacious and the inner peristome very short in Leucodon), or double (Pterogonium, Antitrichia); arising at the mouth of the capsule. The peristome teeth when developed 16; joined basally to form a membranous ring, or not basally joined; not grouped; not deeply cleft; not perforated, or perforated; thin, membranous, and transversely barred; exteriorly with a fine longitudinal dividing line between the transverse bars. The inner peristome when present, well developed to rudimentary; shorter than the outer, or about equalling the outer (?); without a basal membranous ring; with elongated “processes”, or without “processes”. The processes of the inner peristome if present, 16; alternating with the teeth of the outer peristome (the generic name of Antitrichia having been awarded erroneously!). The inner peristome without cilia. The cilia and processes of the endostome not united into a conical lattice. The operculum conical, or rostrate. Setae very short to long; straight, or curved.

Ecology. In diverse habitats.

Cytology. Haploid chromosome number, n = 10–11 (in Leucodon sciuroides).

British representation. 3 species. Antitrichia (Pendulous Wing-moss), Leucodon (Squirrel-tail Mosses), Pterogonium (Bird's-foot Wing-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.

Comments. Sometimes homomallous.

Illustrations. • Antitrichia curtipendula, Leucodon sciuroides and Pterogonium gracile: Dixon. • Leucodon sciuroides and Antitrichia curtipendula: 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.’.