The Moss Families of the British Isles


L. Watson and M. J. Dallwitz


Feather-mosses and Mouse-tail Mosses.


Gametophyte. Pleurocarpous; not dendroid; slender to robust plants, with creeping to ascending stems, branches sometimes homomallous, usually mat or turf forming, or forming patches, or forming wefts. Shoots complanate (rarely), or not complanate. Paraphyllia present (e.g., sometimes in Eurhynchium), or absent (usually). Stems tomentose below, or not tomentose. The leaves of main stems and branches similar in form, or markedly different in form; broadly ovate to narrowly lanceolate; spiral; secund, or not secund (mostly); longitudinally plicate (often, sometimes only weakly), or not plicate. Leaf bases decurrent (in Brachythecium spp., Cirriphyllum, etc.), or not decurrent. The leaves nearly always single-nerved (though occasionally the nerve forked or double, notably in Isothecium myosuroides). The leaf nerves extending beyond the middle of the leaf, but not to the tip (sometimes terminating in a small abaxial projection), or extending to the leaf tip; excurrent (rarely), or not excurrent. Leaf blade apices obtuse, or pointed; apiculate, or not apiculate; apically rounded to acuminate. Leaf blade margins entire, or 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; elongate hexagonal, or rounded, or rhomboidal to linear, or vermicular; nearly always 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 (rarely), or inclined to horizontal (usually); symmetrical to asymmetrical; straight, or curved (commonly); sub-cylindric to ovoid, or pyriform, or gibbous; with an externally conspicuous apophysis, or without an externally conspicuous apophysis; smooth; with an annulus (e.g., in some Brachythecium and Eurhynchium species), or without an annulus. Calyptra glabrous; symmetrical; splitting down one side. Capsules with a peristome. The peristome double. The peristome teeth 16 (these horizontally striate below, and papillose above); not grouped; not deeply cleft; thin, membranous, and transversely barred; exteriorly with a fine longitudinal dividing line between the transverse bars. The inner peristome well developed to reduced; shorter than the outer to exceeding the outer (?); with a basal membranous ring (this high); with elongated “processes”. The processes of the inner peristome 16; alternating with the teeth of the outer peristome. The inner peristome ciliate (the cilia usually well developed), or without cilia (sometimes, in Isothecium). The cilia of the inner peristome when present, nodulose or appendiculate. The operculum conical to rostrate. Setae long; usually curved; usually reddish; smooth, or rough.

Ecology. Occurring in basic habitats (commonly), or neutral pH conditions, or acid conditions (uncommonly?).

Cytology. Haploid chromosome number, n = 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 20, and 22 (often variable within species).

British representation. About 50 species. Brachythecium, Cirriphyllum, Eurhynchium, Homalothecium, Isothecium (Mouse-tail Mosses), Kindbergia, Oxyrrhynchium, Platyhypnidium, Pseudoscleropodium, Rhynchostegiella, Rhynchostegium, Scleropodium, Scorpiurium. 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. The family and generic descriptions perused for this compilation offer no means of distinguishing Amblystegiaceae from Brachytheciaceae at family level.

Illustrations. • Brachythecium and Homalothecium, with Entodontaceae, Leskeaceae and Tomentypnum: Dixon. • Brachythecium (9 species), Cirriphyllum, Pseudoscleropodium and Scleropodium: Dixon. • Cirriphyllum, Eurhynchium, Isothecium, Rhynchostegiella, Scorpiurium: Dixon. • Eurhynchium, Isothecium and 5 Rhynchostegium species: Dixon. • Brachythecium and Homalothecium: Berkeley. • Rhynchostegium (with Amblystegiaceae and Campyliaceae): Berkeley. • Pseudoscleropodium purum, with Calliergonella and Pleurozium: Berkeley. • Homalothecium sericeum, with Hypnaceae and Plagiothecium: Berkeley. • Brachythecium velutinum (by Curtis).

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.’.