The Moss Families of the British Isles


L. Watson and M. J. Dallwitz


Excluding Thamniaceae and Leptodontaceae.

Gametophyte. Pleurocarpous; forming patches. Primary stems procumbent (stoloniform or rhizome-like, the secondary stems decumbent to erect). Shoots complanate. Paraphyllia present, or absent. The leaves of main stems and branches similar in form; more or less markedly asymmetrical, or bilaterally symmetrical to markedly asymmetrical; elliptical to oblong, or ovate, or lanceolate, or lingulate (often asymmetric); spiral. Leaf bases not decurrent. The leaves nerveless, or double-nerved, or single-nerved. The leaf nerves when detectable, not extending beyond the middle of the leaf (Neckera), or extending beyond the middle of the leaf, but not to the tip (in Homalia). Leaf blade apices obtuse, or pointed; apiculate, or not apiculate; apically rounded, or apically acute, or acuminate. Leaf blade margins distally denticulate, or entire. The basal leaf cells longitudinally much elongated; smooth. The walls of basal leaf cells straight. The angular cells clearly differentiated to not well differentiated. The mid-leaf cells longitudinally much elongated; hexagonal to rhomboidal (Homalia), or linear to vermicular (Neckera); smooth. The walls of the mid-leaf cells thick; straight.

Plants monoecious, or dioecious; when monoecious, autoecious.

Sporophyte. Capsules immersed, or immersed to emergent (the seta lacking or very short in Neckera), or exserted; erect (to sub-erect in Homalia); symmetrical; straight; ellipsoid, or ovoid; without an externally conspicuous apophysis; usually without an annulus. Calyptra glabrous, or hairy; symmetrical; splitting down one side. Capsules dehiscing via a lid; 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 reduced, or rudimentary; shorter than the outer to about equalling the outer; with a basal membranous ring; with elongated “processes”. The processes of the inner peristome 16. The inner peristome ciliate (sometimes in Homalia, but the cilia rudimentary only), or without cilia (Neckera). The operculum rostellate, or rostrate, or subulate. Setae usually short; when evident, straight (or somewhat flexuose).

Ecology. Occurring in the Neckera species basic habitats to neutral pH conditions. On rocks, soil banks, walls and tree trunks.

Cytology. Haploid chromosome number, n = 10 and 11 (then sometimes with a supernumerary), or 12.

British representation. 5 species. Neckera (Neckeras), Homalia (Blunt Feather-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.

Illustrations. • Neckera (4 species) and Homalia: Dixon. • Neckera and Homalia, with Leptodon (Leptodontaceae): 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.’.