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

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L. Watson and M. J. Dallwitz

Dumortiera Nees

Gametophyte. Plants thalloid, not leafy. Acrogynous (in that the short-stalked, more or less hemispherical female receptacles are terminal). Rhizoids of two kinds, smooth and tuberculate.

The cells of the gametophyte with numerous small chloroplasts. The thallus branching dichotomously; translucent, with a conspicuous median conducting strand; with ventral scales (these very small and narrowly triangular, ephemeral); without gemma-receptacles; without dorsal pores; without cavities.

The plants dioecious, or bisexual (then monoecious).

The gametangia and capsules borne externally. The archegonia and sporophytes not protected by bracts. The archegonia and sporophytes without a pseudoperianth. The gametangia borne on special ‘receptacles’. The female receptacles long stalked (the stalk with two discoid furrows); about 6-lobed, not rayed. The male receptacles discoid, very shortly stalked (the stalk with two discoid furrows).

Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule usually dehiscing by four valves (but occasionally more). Elaters present; unispirally thickened to bispirally thickened, or thickend via 3–4 spirals; elongate, unbranched, narrowed at each end, free.

British representation. 1 species (D. hirsuta); England, Wales, and Ireland.

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

Illustrations. • D. hirsuta: Jameson, in Macvicar (1926). • D. hirsuta (as irrigua): Pearson fig. CCXIII (1902). • D. hirsuta (as irrigua): Pearson fig. CCXIII 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.’.