The Moss Families of the British Isles


L. Watson and M. J. Dallwitz



~Hypnaceae; excluding Campyliaceae.

Gametophyte. Pleurocarpous; loosely forming tufts, or mat or turf forming, or forming patches. Primary stems erect to procumbent (irregularly branched). Shoots not complanate, or complanate to not complanate (i.e., sub-complanate, in Leptodictyum only). Paraphyllia mostly absent. Pseudoparaphyllia absent (at least, never mentioned). The leaves of main stems and branches similar in form (though the branch leaves are often smaller); mostly ovate to lanceolate (or deltoid); spiral; secund (or sub- or falcato-secund, especially when moist), or not secund; not crisped when dry (except, rarely, towards their tips). Leaf bases not decurrent. The leaves nerveless (rarely), or single-nerved. The leaf nerves when present, not extending beyond the middle of the leaf (rarely), or extending beyond the middle of the leaf, but not to the tip (commonly to about half-way), or extending to the leaf tip (rarely, in Amblystegium); excurrent (sometimes in Amblystegium), or not excurrent (mostly). Leaf blade apices nearly always pointed; mostly not apiculate; apically acute, or acuminate. Leaf blade margins flat; entire, or denticulate. Leaf blades not conspicuously bordered. The basal leaf cells longitudinally much elongated (mostly), or somewhat longitudinally elongated; hexagonal to rhomboidal, or linear; smooth. The walls of basal leaf cells thin, or thick; straight. The angular cells not well differentiated. The mid-leaf cells more or less isodiametric to longitudinally much elongated; narrowly hexagonal, or rounded, or rhomboidal to linear; smooth. The walls of the mid-leaf cells thin to thick; straight.

Plants monoecious, or dioecious (rarely); when monoecious, autoecious.

Sporophyte. Capsules exserted; inclined to horizontal; at least somewhat asymmetrical; curved; sub-cylindric to ellipsoid (often somewhat contracted below the mouth after dehiscence); without an externally conspicuous apophysis; smooth; mostly with an annulus. Calyptra glabrous; symmetrical; splitting down one side. Capsules with a peristome. The peristome double. The peristome teeth 16; not basally joined; not grouped; not deeply cleft; not perforated; thin, membranous, and transversely barred (often distinctly articulated); exteriorly with a fine longitudinal dividing line between the transverse bars. The inner peristome well developed; shorter than the outer to exceeding the outer (?); with a basal membranous ring; with elongated “processes” (these broad). The processes of the inner peristome 16; alternating with the teeth of the outer peristome. The inner peristome ciliate. The cilia of the inner peristome nodulose or appendiculate. The operculum shortly mamillate, or conical. Setae long; usually curved (?); reddish; smooth.

Ecology. Aquatic to mesophytic; occurring in basic habitats (commonly), or neutral pH conditions, or acid conditions. Mostly found in moist, wet or aquatic habitats - especially fens, marshes, dune slacks, basic flushes, etc.

Cytology. Haploid chromosome number, n = 10, 11, 12, 13, 19, 20, 21, 22, 24, 28, 30, 40, and 46 (occasionally with supernumeraries).

British representation. 8 species. Amblystegium, Hygroamblystegium, Leptodictyum. 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. • 6 species of Amblystegium, and Conardia: Dixon. • Amblystegium (with Campyliaceae and Rhyncostegium): Berkeley. • Hygromblystegium and Leptodictyum (with Cratoneuron and Campyliaceae): Dixon.

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.’.