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

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L. Watson and M. J. Dallwitz

Targionia L.

Gametophyte. Plants thalloid, not leafy. Anacrogynous (in that the the sessile female receptacles arise on the ventral side of the thallus apices). Rhizoids of two kinds, smooth and tuberculate.

The cells of the gametophyte with numerous small chloroplasts. The thallus branching dichotomously; with ventral scales (large, persistent, imbricate, with one row on either side of the midrib, semi-lunar with a toothed appendage, purplish-black becoming glossy black when dry).

The plants bisexual; having the gametangia grouped into bracteate inflorescences; autoecious.

The archegonia and sporophytes protected by bracts (with a bilobed involucre and no psuedoperianth). The archegonia and sporophytes without a pseudoperianth. The gametangia borne on special ‘receptacles’. The female receptacles sessile (on the underside of the thallus); not rayed. The male receptacles on short lateral branches.

Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule dehiscing irregularly. The spores unicellular when shed. Elaters present (sometimes branched); bispirally thickened; free.

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

Classification. Class/Division Hepaticae. Subclass/Class Marchantiidae. Order Marchantiales. Family Targoniaceae.

Illustrations. • T. hypophylla: Jameson, in Macvicar (1926). • T. hypophylla: Pearson fig. CCXIV (1902). • T. hypophylla: Pearson fig. CCXIV 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.’.