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

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L. Watson and M. J. Dallwitz

Pellia Raddi

Gametophyte. Plants thalloid, not leafy. Anacrogynous. Rhizoids colourless (numerous, on the ventral surface of the midrib); of one kind, all smooth.

The cells of the gametophyte with numerous small chloroplasts. The thallus branching dichotomously (with emarginate apices); with a conspicuous median conducting strand to without a conspicuous conducting strand (the midrib poorly defined); without ventral scales. Gemmae absent. The thallus without dorsal pores; without Nostoc-cavities and without cavities.

The plants dioecious, or bisexual (monoecious); with no grouping of gametangia into bracteate inflorescences.

The gametangia and capsules immersed in the thallus (solitary, in cavities on the dorsal side of the midrib). The archegonia and sporophytes not protected by bracts. The archegonia and sporophytes in cavities, several per cavity, on the dorsal side of the midrib, with a pseudoperianth (the pseudoperianth flap-like, shortly cylindrical or tubular). Calyptra present and well developed (this thick walled, fleshy, emergent or not from the pseudoperianth).

Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule globose. The capsule wall 2–3 layered. The capsule dehiscing by four valves. The spores unicellular when shed (ovoid). Elaters present; bispirally thickened to thickend via 3–4 spirals (2–4 spiral); persistent on elaterophores. The elaterophores basal.

British representation. 4 species; England, Wales, Scotland, and Ireland.

Classification. Class/Division Hepaticae. Subclass/Class Jungermanniidae. Order Metzgeriales. Family Pelliaceae.

Illustrations. • P. endivifolia (as fabbroniana): Jameson, in Macvicar (1926). • cf. P. endivifolia (as P. calycina): Pearson fig. CXCVIII (1902). • cf. P. endivifolia (as P. calycina): Pearson fig. CXCVIII legend. • P. epiphylla: Jameson, in Macvicar (1926). • P. epiphylla: Pearson fig. CXCVII (1902). • P. epiphylla: Pearson fig. CXCVII ;egend. • P. neesiana: Jameson, in Macvicar (1926).

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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.’.