| | 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.
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 liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland. Version: 5th August 2019. delta-intkey.com’.
