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| The moss families (Bryophyta, Musci) of Britain and Ireland |
Tamarisk-mosses.
Excluding Anomodontaceae (Anomodon)
Gametophyte. Pleurocarpous; forming patches, or forming wefts (the branches often arcuate or homomallous). Shoots complanate, or not complanate (Abietinella). Paraphyllia present. The leaves of main stems and branches markedly different in form; ovate to narrowly lanceolate (sometimes deltoid), or lingulate; spiral. Leaf bases decurrent (Heterocladium), or not decurrent. The leaves double-nerved (Heterocladium), or single-nerved (Thuidium). The leaf nerves extending beyond the middle of the leaf, but not to the tip. Leaf blade apices obtuse, or pointed; apiculate, or not apiculate; apically acute, or acuminate. Leaf blade margins entire, or denticulate to dentate (or crenulate). Leaf blades not conspicuously bordered. The basal leaf cells somewhat longitudinally elongated to longitudinally much elongated; papillose. The angular cells not well differentiated. The mid-leaf cells somewhat longitudinally elongated, or longitudinally much elongated (Heterocladium, Helodium); hexagonal, or rounded, or rhomboidal; papillose. The walls of the mid-leaf cells thin to thick; straight, or sinuous.
Plants monoecious, or dioecious (mostly).
Sporophyte. Capsules exserted; inclined; curved; with an annulus. Calyptra symmetrical; splitting down one side. Capsules with a peristome. The peristome double. The peristome teeth not grouped; not deeply cleft; not perforated; thin, membranous, and transversely barred; exteriorly with a fine longitudinal dividing line between the transverse bars. The inner peristome well developed; shorter than the outer; with a basal membranous ring; with elongated “processes”; ciliate. The operculum conical, or mamillate, or rostrate. Setae long; reddish.
Ecology. Occurring in basic habitats, neutral pH conditions, and acid conditions. In diverse habitats.
Cytology. Haploid chromosome number, n = 10, 11, and 12.
Representation in Britain and Ireland. 9 species. Abietinella, Heterocladium (cf. Pterigynandraceae), Thuidium. 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 (see classificatory comment under Pterigynandraceae).
Comments. The ‘fronds’ of Thuidium tamariscinum, comprising regularly, usually thrice-pinnately branched secondary stems, render this common species one of the most easily identified of British and Irtish mosses.
Illustrations. • Heterocladium: Dixon. THUIDIACEAE or Pterigynandraceae: M, Heterocladium heteropterum (Schwaegr.) Br. Eur.; N, Heterocladium macounii Best (a North American species occasionally reported from Britain and mainland Europe); O, Heterocladium dimorphum Br. Eur.
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. • Abietinella and Thuidium, with Helodium: Dixon. THUIDIACEAE: C, Abietinella abietinum (Hedw.) Fleisch.; D, Abietinella abietinum ssp. hystricosum (Mitt.) Kindb.; F, Thuidium tamariscinum (Hedw.) Br. Eur.; G, Thuidium delicatulum (Hedw.) Mitt.; H, Thuidium recognitum (Hedw.) Lindb.; I, Thuidium assimile (Mitt.) Jaeger. HELODIACEAE: E, Helodium blandowii (Web. & Mohr) Warnst.
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. • Thuidium, with Anomodon and Helodium: Berkeley. THUIDIACEAE: 4, Thuidium tamariscinum (Hedw.) Br. Eur.; a, leaves; b, capsule. ANOMODONTACEAE: 6, Anomodon veticulosus (Hedw.) Hook. & Tayl.; a, leaf; b, capsule; c; part of peristome, from the inside. HELODIACEAE: 5, Helodium blandovii (Web. & Mohr) Warnst.; a, stem leaf from above; b, stem leaf from below, showing paraphylla; c, capsule; d, branch leaf.
From Berkeley (1863, Plates 8 and 13). 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’.
