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

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L. Watson and M. J. Dallwitz

Aneura Dum.

~ Riccardia.

Gametophyte. Plants thalloid, not leafy (the brittle thallus yellowish to dark green, plano-convex to deeply concave, the margins often more or less crisped). Anacrogynous. Rhizoids present (abundant); of one kind, all smooth.

The cells of the gametophyte with numerous small chloroplasts. The chloroplast-containing cells with conspicuous oil bodies (6–30 per cell, present in all the cells). The thallus sparsely and irregularly pinnately branching, or simple (the apices rounded, not emarginate); greasy in appearance; without a conspicuous conducting strand (the midrib poorly defined). Gemmae absent. The thallus with gemma-receptacles on the surface; without dorsal pores; without cavities.

The plants dioecious.

The gametangia and capsules borne externally (on short lateral branches). Calyptra present and well developed (5–12 cells thick).

Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule wall 2 layered. The capsule dehiscing by four valves. The spores unicellular when shed. Elaters present; unispirally thickened (with a single, reddish brown band); persistent on elaterophores, or free and persistent on elaterophores. The elaterophores apical (at dehiscence splitting into four, resulting in erect tufts of elaters at the valve apices).

British representation. 1 species (A. pinguuis); England, Wales, Scotland, and Ireland.

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

Illustrations. • A. pinguis: Jameson, in Macvicar (1926). • A. pinguis: Pearson fig. CCIV (1902). • A. pinguis: Pearson fig. CCIV 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.’.