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| The moss families (Bryophyta, Musci) of Britain and Ireland |
Nut-mosses.
Formerly included in Buxbaumiaceae
Gametophyte. Acrocarpous; forming patches, or the plants scattered. Minute, almost stemless plants. Mature plants about 0.5–5 mm high. Leaves present. The leaves lanceolate, or lingulate; crisped when dry. Leaf bases slightly sheathing to not sheathing. The leaves single-nerved. The leaf nerves extending beyond the middle of the leaf, but not to the tip (though excurrent in the perichaetial leaves). Leaf blade apices obtuse to pointed; apically rounded to apically acute. Leaf blade margins unistratose (the body of the lamina unistratose basally, but 2(-3) stratose above). The basal leaf cells more or less isodiametric to somewhat longitudinally elongated; rectangular, or hexagonal, or rounded; smooth. The walls of basal leaf cells thin to thick; straight. The angular cells not well differentiated. The mid-leaf cells more or less isodiametric; quadrate to rhomboidal; papillose. The walls of the mid-leaf cells thick; straight.
Plants dioecious.
Sporophyte. Capsules immersed to emergent (sub-sessile); inclined; asymmetrical; slightly curved, or straight; obliquely ovoid, or gibbous (somewhat); with an externally conspicuous apophysis, or without an externally conspicuous apophysis. Calyptra very small; symmetrical. Capsules with a peristome. The peristome single (representing the inner peristome, cf. haplolepideous mosses in general, but as in Buxbaumia taking the form of a pale, plicate membrane). The inner peristome with only 16 longitudinal plicae, contrasting with the 34-plicate membrane of Buxbaumia. The operculum narrowly conical. Setae short or long; straight.
Cytology. Haploid chromosome number, n = 9.
Representation in Britain and Ireland. 1 species (D. foliosum being common in montane areas, rare elsewhere). Diphyscium (Nut-moss). Northern Scotland, southern Scotland, northern England, English Midlands, Wales, central southern England, southwest England, and Isle of Wight.
Classification. Class Bryopsida; Subclass Diphysciideae; Order Diphysciales.
Illustrations. • Diphyscium foliosum, with Buxbaumia: Dixon. DIPHYSCIACEAE: D, Diphyscium foliosum (Hedw.) Mohr. BUXBAUMIACEAE: B, Buxbaumia aphylla Hedw.; C, Buxbaumia viridis (Moug. ex DC) Brid. ex Moug. & Nestle.
From Dixon and Jameson (1924), the unscaled screen display approximately doubling the magnifications given with their individual figures. 1, leaf or stem leaf where these differ; 2, branch-leaf; 3, perichaetial leaf; 4, perigonial leaf; 5, capsule; 6, peristome; 7, calyptra; 8, spores; 9, inflorescence; 10, gemmae; 11, paraphyllia; 12, stoma of capsule; *, plant, or part of one. Qualifications: a, apex; b, base; c, cells at one third from the apex; cv, ventral aspect of cells; cd, dorsal aspect of cells; bc, basal cells; x, section. Buxbaumia aphylla. Buxbaumia viridis. Diphyscium foliosum. • Diphyscium foliosum, with Buxbaumia aphylla: Berkeley. DIPHYSCIACEAE: 5, Diphyscium foliosum (Hedw.) Mohr; a, habit; b, plant, more enlarged; c, capsule; d, calyptra; e, peristome; f, leaf (green) and two perichaetial bracts (brown). BUXBAUMIACEAE: 6, Buxbaumia aphylla Hedw.; a, habit (the plants leafless); b, sporangium; c, calyptra; d, peristome; e, a process from the inner peristome.
From Berkeley (1863, Plate 19). The approximate 1 cm scale applies to the whole plant (habit) illustrations only.
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, 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. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2005 onwards. The moss families (Bryophyta, Musci) of Britain and Ireland. Version: 5th August 2019. delta-intkey.com’.
