The Moss Families of the British Isles


L. Watson and M. J. Dallwitz


Apple-mosses, etc.

Excluding Catoscopiaceae.

Gametophyte. Pleurocarpous (e.g., Bartramia hallerana, Breutelia arcuata), or acrocarpous (mostly); mostly forming tufts. Mature plants when erect or ascending, from about 2–150 mm high. Stems tomentose below. The leaves ovate to lanceolate, or narrowly lanceolate (mostly narrow); spiral (or 5-ranked, in Conostomum); when moist, secund (or sub-secund), or not secund; crisped when dry, or not crisped when dry (mostly). Leaf bases sheathing (sometimes), or not sheathing. The leaves single-nerved. The leaf nerves extending beyond the middle of the leaf, but not to the tip, or extending to the leaf tip; excurrent, or not excurrent. Leaf blade apices pointed; mostly acuminate. Leaf blade margins denticulate to dentate (sometimes doubly toothed), or entire. The basal leaf cells more or less isodiametric; papillose, or smooth. The walls of basal leaf cells thin, or thick; straight. The angular cells not well differentiated. The mid-leaf cells more or less isodiametric, or somewhat longitudinally elongated to longitudinally much elongated; quadrate, or rectangular, or hexagonal, or rounded, or rhomboidal, or linear, or vermicular (but usually short and narrow and sub-rectangular); ostensibly papillose (often being mamillose). The walls of the mid-leaf cells thin to thick; straight.

Plants monoecious (mostly), or dioecious (e.g., Conostomum); autoecious, or synoecious.

Sporophyte. Capsules exserted; erect, or inclined (cernuous, usually), or horizontal, or pendulous (Breutelia); more or less symmetrical, or asymmetrical (the mouth often oblique); when elongate, straight, or curved; more or less globose, or pyriform, or gibbous (in Conostomum,); without an externally conspicuous apophysis; smooth (in some Philonotis species), or striate and becoming regularly furrowed when dry and empty. Calyptra very small; symmetrical; splitting down one side. Capsules with a peristome (usually), or without a peristome (often, in Bartramidula). The peristome when present, single (Conostomum, some Bartramia), or double (usually). The peristome teeth when present, 16; apically joined (Conostomum), or apically free; not grouped; not deeply cleft; not perforated, or perforated (if the situation on Conostomum is interpreted as perforation); thin, membranous, and transversely barred; when present, exteriorly with a fine longitudinal dividing line between the transverse bars. The inner peristome when present, well developed to rudimentary; shorter than the outer; with a basal membranous ring; with elongated “processes” (these divided); ciliate (the cilia well developed or rudimentary), or without cilia. The operculum convex, or conical, or mamillate. Setae long; curved (sometimes cygneous), or straight, or flexuose.

Ecology. In wet places; occurring in basic habitats, or neutral pH conditions, or acid conditions (often). Often in rock crevices, on stone walls, etc., by streamsides or on damp rocks or in damp or peaty soil, sometimes at high altitudes.

Cytology. Haploid chromosome number, n = 6, 7, 8, 12, and 16.

British representation. 16 species. Bartramia, Bartramidula (~Philonotis), Breutelia (Golden-head Moss), Conostomum (Helmet-moss), Philonotis, Plagiopus. 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 Bryales.

Illustrations. • Bartramia, Conostomum and Plagiopus: Dixon. • Bartramia and Philonotis: Dixon. • Breutelia chrysocoma: Dixon. • Bartramia, Conostomum and Plagiopus: 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.’.