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

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L. Watson and M. J. Dallwitz

Bazzania S.F. Gray

Gametophyte. Plants plants small to robust, as tufts, mats or scattered shoots leafy. The stems apparently branching dichotomously. The branching dichotomous. The stems with no clear differentiation of cortical and central tissues (though the cortical cells tend to be larger). Plants with flagella or flagelliform shoots or branches (these ventral). Acrogynous. The leaf cells with 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 usually very transversely inserted (usually asymmetrical with arched dorsal margin); alternate; overlapping to distant; apically bilobed to several-lobed (or toothed); without vittae. Underleaves smaller than the laterals though well developed and conspicuous (smaller, entire or 2-several lobed, entire or dentate). The cells of the gametophyte with numerous small chloroplasts.

The plants when fertile, dioecious.

Male inflorescences on short ventral branches, with 4–6 pairs of concave, bi-lobed or -toothed bracts that are smaller than the leaves. Female inflorescences on short ventral branches. Female bracts present (smaller than the leaves, ovate to ovate-lanceolate, often apically lobed and the margins dentate to ciliate). Perianth present; several-stratose below to unistratose above, rhe mouth dentate or ciliate.

Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule wall 4–6 layered (the innermost layer with semi-annular thickenings). The spores unicellular when shed. Elaters present; when recorded, bispirally thickened; free.

British representation. 3 species; England, Wales, Scotland, and Ireland.

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

Illustrations. • B. trilobata: Jameson, in Macvicar (1926). • B. trilobata: Pearson fig. XLVII (1902). • B. trilobata: Pearson fig. XLVII legend. • B. tricrenata: Jameson, in Macvicar (1926). • B. tricrenata: Pearson fig. XLIX (1902). • B. tricrenata: Pearson fig. XLIX legend. • B. tricrenata (as triangularis): Pearson fig. XLVIII (1902). • B. tricrenata (as triangularis): Pearson fig. XLVIII legend. • B. pearsonii: Jameson, in Macvicar (1926). • B. pearsonii (as pearsoni): Pearson fig. L (1902). • B. pearsonii (as pearsoni): Pearson fig. L 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.’.