The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland
Gametophyte. Plants thalloid, not leafy. Anacrogynous (in that archegonia are embedded in the dorsal surface of the thallus). Rhizoids of two kinds, smooth and tuberculate.
The cells of the gametophyte with numerous small chloroplasts. The thallus grooved, with conspicuous ventral scales, branching dichotomously (often cordate); with ventral scales (conspicuous, brownish to violet, serrate); without gemma-receptacles; with conspicuous dorsal pores (and with scattered oil-cells). The pores small but distinct simple. The thallus containing conspicuous cavities. The air chambers usually irregularly distributed.
The plants dioecious, or bisexual (then monoecious).
The gametangia not borne on special receptacles (embedded in the dorsal surface of the thallus).
Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. Elaters absent. Ecology. Floating aquatic, or in wet places, or mesophytic; occurring in basic habitats.
British representation. 1 species (R. natans); England and Ireland.
Classification. Class/Division Hepaticae. Subclass/Class Marchantiidae. Order Marchantiales. Family Ricciaceae.
Illustrations. • R. natans: Jameson, in Macvicar (1926). • R. natans: Pearson fig. CCXXV (1902). • R. natans: Pearson fig. CCXXV 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. delta-intkey.com’.