The Moss Families of the British Isles


L. Watson and M. J. Dallwitz


Excluding Myriniaceae.

Gametophyte. Pleurocarpous; forming patches, or growing through other Bryophytes. Primary stems procumbent (and homomallous). Paraphyllia absent. The leaves of main stems and branches similar in form; bilaterally symmetrical; ovate (to deltoid, concave); spiral. Leaf bases not decurrent. The leaves nerveless, or single-nerved. The leaf nerves when present, not extending beyond the middle of the leaf, or extending beyond the middle of the leaf, but not to the tip. Leaf blade apices pointed; not apiculate; apically acute, or acuminate. Leaf blade margins flat; unistratose; finely crenulate or entire. Leaf blades not conspicuously bordered. The basal leaf cells longitudinally much elongated; rounded, or rhomboidal; smooth. The walls of basal leaf cells thick; straight. The angular cells clearly differentiated to not well differentiated. The mid-leaf cells somewhat longitudinally elongated to longitudinally much elongated; rounded to rhomboidal; smooth. The walls of the mid-leaf cells thin to thick; straight.

Plants dioecious. Plants gemmiferous (with (1-)2–5 celled, brownish gemmae on young parts of branch stems), or not gemmiferous.

Sporophyte. Capsules exserted; minute; erect; symmetrical; straight; narrowly ellipsoid; with an annulus (large, separating). Calyptra symmetrical; splitting down one side. Capsules with a peristome. The peristome single (the inner peristome lacking); arising below the mouth of the capsule. The peristome teeth 16 (?); not grouped; not deeply cleft; thin, membranous, and transversely barred; exteriorly with a fine longitudinal dividing line between the transverse bars. The operculum conical. Setae short; straight.

Ecology. Mesophytic. On tree trunks.

British representation. 1 species. Habrodon (Squirrel-tail Moss). Southern Scotland, northern England, English Midlands, Wales, and southwest England.

Classification. Class Bryopsida; Subclass Bryideae; Order Hypnales.

Illustrations. • Habrodon perpusillus (with Myrinia): Dixon. Habrodon perpusillus Lindb. Myrinia pulvinata Schp.

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.’.