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| The moss families (Bryophyta, Musci) of Britain and Ireland |
Yoke-mosses.
~Dicranaceae, Rhabdoweisiaceae
Gametophyte. Acrocarpous; densely cushion-forming. Mature plants to 40–80 mm high. Stems not tomentose; with a differentiated central strand. The leaves of main stems and branches similar in form; lanceolate to linear, or lingulate; not distichous; spiral; not secund; crisped when dry. Leaf bases not sheathing; not decurrent. The leaves single-nerved. The leaf nerves extending beyond the middle of the leaf, but not to the tip to extending to the leaf tip; not excurrent; incorporating stereids, or without stereids. Leaf blade apices pointed; not apiculate; apically acute, or acuminate; not hyaline. Leaf blade margins revolute or recurved (on one or both sides); unistratose; distally denticulate, or entire. Leaf blades not conspicuously bordered. The basal leaf cells somewhat longitudinally elongated to longitudinally much elongated; rectangular; 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; hexagonal to rounded; papillose. The walls of the mid-leaf cells thick; straight.
Plants monoecious, or dioecious (in A. mougeotii); in A. lapponicum, autoecious. Parapyhyses absent.
Sporophyte. Capsules emergent to exserted; erect; symmetrical; straight; narrowly pyriform; not waisted; without an externally conspicuous apophysis; striate and becoming regularly furrowed when dry and empty; without an annulus. Calyptra splitting down one side. Capsules dehiscing via a lid; without a peristome. Setae present; very short; straight.
Ecology. Mesophytic and xerophytic; occurring in basic habitats (A. lapponicum), or neutral pH conditions, or acid conditions (A. mougeotii). On cliffs and rock outcrops or in crevices, in ravines and woods, coastal and inland.
Cytology. Haploid chromosome number, n = 13 (A. lapponicum).
Representation in Britain and Ireland. 2 species. Amphidium. Northern Scotland, southern Scotland, northern England, Wales, southwest England, and Ireland.
Classification. Class Bryopsida; Subclass Dicranideae, or Bryideae; Order Dicranales, or Orthotrichales.
Illustrations. • Zygodon, with Amphidium: Dixon. AMPHIDIACEAE: E, Amphidium lapponicum (Hedw.) Schimp.; F, Amphidium mougeotii (Br. Eur.) Schimp. ORTHOTRICHACEAE: G, Zygodon viridissimus (Dicks.) R. Br. var. viridissimus; H, Zygodon viridissimus var. stirtonii (Schimp. ex Stirt.) Hagen.; I, Zygodon conoideus (Dicks.) Hook.
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.
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’.
