The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland
Gametophyte. Plants thalloid, not leafy (the thalli forming small rosettes, lobed, multistratose in the middle to unistratose in the lobes, dorsally almost covered with tubular involucres each of which protects an atheridium, an archegonium, or a sporophyte). Anacrogynous (the involucrate gametangia on the surfaces of the thallus). Rhizoids numerous from the middle of the thallus, long and colourless; of one kind, all smooth.
The cells of the gametophyte with numerous small chloroplasts. The thallus irregularly lobed (multistratose in the middle and becoming unistratose in the lobes); with no distinct midrib, without a conspicuous conducting strand; without gemma-receptacles; without dorsal pores; without cavities.
The plants dioecious; with no grouping of gametangia into bracteate inflorescences. The antheridia not protected by bracts (in involucres scattered of the dorsal surfaces of the thallus).
The gametangia and capsules borne externally. The archegonia and sporophytes not protected by bracts. The archegonia and sporophytes without a pseudoperianth (the archegonia in unistratose, clavate or pyriform involucres covering almost the entire dorsal surface of the thasllus). The gametangia not borne on special receptacles. Calyptra present and well developed (closely investing the capsule).
Sporophyte. The sporophyte comprising foot and capsule only. The capsule enclosed by the involucre, more or less globose; indehiscent. The spores dark brown, shed as tetrads. Elaters absent (the sterile cells remaining small and starch-bearing).
British representation. 2 species; England and Wales.
Classification. Class/Division Hepaticae. Subclass/Class Marchantiidae. Order Sphaerocarpales. Family Sphaerocarpaceae.
Illustrations. • S. michelii: Jameson, in Macvicar (1926). • S. michelii (as terrestris): Pearson fig. CCXV (1902). • S. michelii (as terrestris): Pearson fig. CCXV legend. • S. texanus: 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. delta-intkey.com’.