The Moss Families of the British Isles


L. Watson and M. J. Dallwitz


Excluding Rhytidium.


Gametophyte. Pleurocarpous; not dendroid; forming patches, or forming wefts (robust mosses, usually forming patches, or lax, coarse wefts). Primary stems erect to procumbent (the stems usually forked, often pinnately branched). Shoots complanate, or not complanate. Paraphyllia present (only in Hylocomium), or absent. Pseudoparaphyllia present, or absent. Stems reddish. The leaves of main stems and branches similar in form, or markedly different in form (especially in Hylocomium); bilaterally symmetrical; ovate to lanceolate (or deltoid); spiral; (falcato-) secund, or not secund; longitudinally plicate (in Hylocomium), or not plicate. Leaf bases almost sheathing, or not sheathing; not decurrent. The leaves shortly double-nerved, or nerveless. The leaf nerves when present, not extending beyond the middle of the leaf, or not extending beyond the middle of the leaf to 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 flat, or involute or incurved, or revolute or recurved; 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 clearly differentiated, or not well differentiated. The mid-leaf cells longitudinally much elongated; narrowly rhomboidal to linear, or vermicular; smooth. The walls of the mid-leaf cells thick; straight.

Plants dioecious.

Sporophyte. Capsules exserted; inclined, or horizontal, or inclined to horizontal; symmetrical to asymmetrical; usually at least somewhat curved, or straight to curved; sub-cylindric to ovoid, or pyriform, or gibbous; with an externally conspicuous apophysis, or without an externally conspicuous apophysis; smooth; without 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 well developed; shorter than the outer to exceeding the outer (?); with a basal membranous ring; 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 nodulose or appendiculate (nodulose). Setae red; smooth (usually), or rough (then papillose).

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

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

British representation. 9 species. Hylocomiastrum (Wood-moss), Hylocomium (Wood-mosses), Loeskeobryum, Pleurozium (Feather-moss), Rhytidiadelphus (Shaggy- and Turf-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. • Hylocomiastrum, Hylocomium and Rhytidiadelphus (with Rhytidiaceae): Dixon. • Hylocomium, Loeskeobryum and Rhytidiadelphus, with Hyocomium (Hypnaceae): Berkeley. • Rhytidiadelphus (with Campyliaceae, etc.: Berkeley. • Pleurozium, with Calliergonella 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.’.