The Moss Families of the British Isles


L. Watson and M. J. Dallwitz



In Dixon’s Meesiaceae.

Gametophyte. Acrocarpous; forming tufts, or forming patches. Stems tomentose below. The leaves ovate to lanceolate; spiral; crisped when dry, or not crisped when dry; single-nerved. The leaf nerves extending beyond the middle of the leaf, but not to the tip. Leaf blade apices obtuse to pointed; apiculate to not apiculate; apically rounded to acuminate. Leaf blade margins revolute or recurved (on one or both sides), or revolute or recurved; entire, or denticulate. Leaf blades not conspicuously bordered. The basal leaf cells more or less isodiametric to somewhat longitudinally elongated (or enlarged); papillose. The walls of basal leaf cells thick. The angular cells not well differentiated. The mid-leaf cells more or less isodiametric, or more or less isodiametric to somewhat longitudinally elongated; hexagonal to rounded; papillose (usually both adaxially and abaxially, with a single conical papilla). The walls of the mid-leaf cells thick; straight, or sinuous.

Plants dioecious. Plants gemmiferous (A. palustre), or not gemmiferous; the gemmae of A. palustre in terminal clusters on the ends of flagelliform pseudopodia.

Sporophyte. Capsules exserted; slightly inclined (or curved), or horizontal; straight, or straight to curved; more or less ovoid to pyriform, or sub-cylindric to ellipsoid; with an externally conspicuous apophysis to without an externally conspicuous apophysis; striate and becoming regularly furrowed when dry and empty. Calyptra glabrous; symmetrical; splitting down one side. Capsules with a peristome. The peristome double. The peristome teeth 16; not deeply cleft; thin, membranous, and transversely barred; exteriorly with a fine longitudinal dividing line between the transverse bars. The inner peristome well developed; with a basal membranous ring; with elongated “processes”. The processes of the inner peristome 16; alternating with the teeth of the outer peristome. The inner peristome ciliate. The operculum rostrate. Setae long; straight.

Ecology. In wet places (A. palustre being common in bogs), or mesophytic; occurring in neutral pH conditions, or acid conditions. Forming tufts or patches in bogs, acid flushes, wet places in montane heaths and moors; mostly not saxicolous, but A. androgynum on damp rocks or decaying wood, or in knot holes or crevices in bark;.

Cytology. Haploid chromosome number, n = 10, 11, and 12.

British representation. 3 species. Aulacomnium. 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 Bryales.

Comments. The branches often terminating in flagelliform pseudopodia, these naked or with only a few minute leaves, and bearing a cluster of gemmae at the tip.

Illustrations. • Aulacomnium androgynum, A. palustre and A. turgidum: Dixon. • Aulacomnium palustre: 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.’.