The Moss Families of the British Isles


L. Watson and M. J. Dallwitz



Gametophyte. Acrocarpous; cushion-forming, or forming tufts (the stems rooting only at their bases, the leaves usually conspicuously hygroscopic). Mature plants 5–80(–100) mm high. The branches in fascicles. The leaves bilaterally symmetrical to markedly asymmetrical (often curved to one side); ovate to narrowly lanceolate, or spathulate to obovate, or linear (then abruptly narrowed above the base to become so); spiral; secund (or curved to one side, often), or not secund; not crisped when dry; nerveless, or single-nerved. The leaf nerves when present extending beyond the middle of the leaf, but not to the tip, or extending to the leaf tip; excurrent (slightly, in A. crassinervia), or not excurrent. Leaf blade apices obtuse to pointed; apiculate, or not apiculate; apically rounded to acuminate. The basal leaf cells somewhat longitudinally elongated, or longitudinally much elongated; papillose, or smooth. The walls of basal leaf cells thick; straight, or sinuous. The angular cells not well differentiated. The mid-leaf cells more or less isodiametric to somewhat longitudinally elongated; quadrate to rectangular, or rounded; papillose, or smooth. The walls of the mid-leaf cells thick; sinuous.

Plants monoecious, or dioecious (A. nivalis only); when monoecious, autoecious.

Sporophyte. Capsules exserted (the mature capsule becoming exserted via a “pseudopodium”, which develops by elongation of the basal part of the sporogonium); erect; symmetrical; ellipsoid to ovoid, or pyriform; with an externally conspicuous apophysis. Calyptra small; symmetrical; with two or more splits. Capsules dehiscing via longitudinal slits (i.e., the lid persisting, instead of being shed in the usual fashion); without a peristome. Setae absent.

Ecology. Occurring in basic habitats, neutral pH conditions, and acid conditions. Growing on basic and acidic rocks, mostly at high altitudes or montane.

Cytology. Haploid chromosome number, n = 9 (+ m), or 10, or 11 (for the three species recorded).

British representation. 11 species. Andreaea. Northern Scotland, southern Scotland, northern England, English Midlands, Wales, southeast England, and Ireland.

Classification. Class Andraeopsida; Order Andreaeales.

Comments. Plants very fragile, reddish purple or brown to blackish.

Illustrations. • Andreaea: Dixon. • Andreaea and Sphagnum: 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.’.