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

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L. Watson and M. J. Dallwitz

Riccia L.

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 branching dichotomously; with ventral scales (arising in a single median row, becoming two lateral rows of half-scales by growth of the thallus); without gemma-receptacles; without epidermal oil-cells, with inconspicuous dorsal pores, or without dorsal pores. The pores if present, simple (vestigial). The thallus containing conspicuous cavities (in 4–5 rows). The air chambers in several layers in section, or irregularly distributed.

The plants dioecious, or bisexual (then monoecious).

The gametangia and capsules immersed in the thallus. 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. The capsule decaying to release the spores?. The spores unicellular when shed (released by decay of the thallus). Elaters absent. Ecology. Submerged aquatic, or in wet places to mesophytic.

British representation. 13 species; England, Wales, Scotland, and Ireland.

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

Illustrations. • R. beyrichiana: Jameson, in Macvicar (1926). • cf. R. beyrichiana (as glaucescens): Pearson fig. CCXXII (1902). • cf. R. beyrichiana (as glaucescens): Pearson fig. CCXXII legend. • R. bifurca: Jameson, in Macvicar (1926). • R. bifurca: Pearson fig. CCXIX (1902). • R. bifurca: Pearson fig. CCXIX legend. • R. crozalsii: Jameson, in Macvicar (1926). • R. crystallina: Jameson, in Macvicar (1926). • R. crystallina: Pearson fig. CCXVII (1902). • R. crystallina: Pearson fig. CCXVII legend. • R. fluitans: Jameson, in Macvicar (1926). • R. fluitans (as Ricciella): Pearson fig. CCXXIV (1902). • R. fluitans (as Ricciella): Pearson fig. CCXXIV legend. • R. glauca: Jameson, in Macvicar (1926). • R. glauca: Pearson fig. CCXVI (1902). • R. glauca: Pearson fig. CCXVI legend. • R. huebeneriana: Jameson, in Macvicar (1926). • R. nigrella: Pearson fig. CCXX (1902). • R. nigrella: Pearson fig. CCXX legend. • R. sorocarpa: Jameson, in Macvicar (1926). • R. sorocarpa: Pearson fig. CCXVIII (1902). • R. sorocarpa: Pearson fig. CCXVIII legend. • R. subbifurca (as warnstorfii): Jameson, in Macvicar (1926). • R. subbifurca (as commutata): Jameson, in Macvicar (1926).

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.’.