The Moss Families of the British Isles


L. Watson and M. J. Dallwitz



Gametophyte. Pleurocarpous; mat or turf forming (the plants slender to moderately robust, soft and glossy). Primary stems procumbent (stems irregularly pinnately branched, tomentose). Mature plants with the procumbent shoots to about 80 mm long in C. laetevirens. Shoots complanate. The leaves more or less markedly asymmetrical; broadly ovate; spiral (5–8 ranked). Leaf bases not decurrent. The leaves double-nerved. The leaf nerves not extending beyond the middle of the leaf to extending beyond the middle of the leaf, but not to the tip (to about halfway). Leaf blade apices pointed; apiculate. Leaf blade margins unistratose to bi-stratose; entire to denticulate (apically denticulate). Leaf blades narrowly bordered. The basal leaf cells somewhat longitudinally elongated; irregularly to elongate hexagonal; smooth. The walls of basal leaf cells thin; straight. The angular cells not well differentiated. The mid-leaf cells somewhat longitudinally elongated; irregularly hexagonal, or rounded; smooth. The walls of the mid-leaf cells thin; straight.

Plants monoecious, or dioecious; autoecious, or synoecious.

Sporophyte. Capsules exserted; inclined to horizontal; symmetrical; straight; sub-cylindric, or ovoid; not waisted; neither flattened nor angular; without an externally conspicuous apophysis; smooth; with an annulus (comprising a single row of fugacious cells). Calyptra hairy; symmetrical; with two or more splits. 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 about equalling the outer; with a basal membranous ring (this high); with elongated “processes” (these keeled). The processes of the inner peristome 16; alternating with the teeth of the outer peristome. The inner peristome ciliate, or without cilia (?). The operculum rostrate. Setae long, stout; straight; smooth.

Ecology. In wet places. On wet shaded rocks, in ravines, caves and crevices near waterfalls.

British representation. 1 species. Cyclodictyon (Bright-Green Cave-moss). Southwest England and Ireland (extinct in England?).

Classification. Class Bryopsida; Subclass Bryideae; Order Hookeriales.

Illustrations. • Cyclodictyon, Daltonia, and Hookeria: Dixon. Daltonia splachnoides. Cyclodictyon laetevirens. Hookeria lucens. • Cyclodictyon, with Fontinalaceae, Cryphaeaeae, Hookeriaceae,: 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.’.