The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland

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L. Watson and M. J. Dallwitz

Trichocolea Dum.

Gametophyte. Plants small to robust, pale to whitish green, leafy. The stout stems 1–3 pinnate, branching laterally. Plants with paraphyllia amongst the leaves (these branched). Acrogynous. The leaf cells without trigones.

The leafy shoots dorsiventral, with two equal ranks of lateral leaves and a third, ventral rank of smaller underleaves. The vegetative leaves markedly asymmetrical. The vegetative leaves transversely inserted to obliquely inserted; alternate; overlapping, or distant; spreading, not conduplicate, succubous. The leaf margins multi-ciliate (the leaves being almost entirely dissected into numerous cilia). The vegetative leaves several-lobed (palmately 4–7 lobed almost to their bases, the primary lobes with long-tapering to uniseriate secondary lobes); without vittae. Underleaves smaller than the laterals though well developed and conspicuous (bilobed). The cells of the gametophyte with numerous small chloroplasts. Gemmae absent.

The plants dioecious.

Male inflorescences on lateral branches, the bracts similar to the leaves, the underleaves without antheridia. Male bracts subtending a single antheridium, or 2 antheridia. Female inflorescences of the conventional kind lacking, the archegonia terminating main branches and/or axes, becoming lateral by development of innovation. Perigynium present and well developed (this representing prolonged stem tissue, enclosing the capsule, narrowly ellipsoid and covered with paraphyllia, with a ciliate mouth). Female bracts present (similar to the leaves). Perianth absent.

Sporophyte. The sporophyte long-pedicellate, elevated by elongation of the seta, with no intercalary meristem (terminal on a main axis or or branch, becoming lateral by innovation). The capsule ovoid to shortly cylindrical (obloid). The capsule wall 6–8 layered. The capsule purplish brown. The spores unicellular when shed. Elaters present; bispirally thickened; free.

British representation. 1 species (T. tomentella); England, Wales, Scotland, and Ireland.

Classification. Class/Division Hepaticae. Subclass/Class Jungermanniidae. Order Jungermanniales. Family Trichocoleceae.

Illustrations. • T. tomentella: Jameson, in Macvicar (1926). • T. tomentella: Pearson fig. XL (1902). • T. tomentella: Pearson fig. XL legend.

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 liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland. Version: 24th February 2016.’.