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| The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland |
Gametophyte. Plants dull green, reddish-brown or brownish-black, leafy. The branching of the Frullania type. The stems with cortical cells clearly differentiated from the cells of the central strand, or with no clear differentiation of cortical and central tissues. Acrogynous. The leaf cells with trigones, or without trigones. Rhizoids present (arising from the bases of the underleaves).
The leafy shoots dorsiventral, with two equal ranks of lateral leaves and a third, ventral rank of smaller underleaves. The vegetative leaves almost transversely inserted, or transversely inserted to obliquely inserted (spreading more or less horizontally, overlapping the stem on the dorsal side, sometimes caducous); alternate; overlapping; incubous (if determinable); deeply bilobed (almost to the base, the dorsal lobe orbicular to ovate or obliquely so, entire, the much smaller ventral lobes mostly helmet shaped or saccate, occasionally evolute); complicate-bilobed. The ventral lobes much smaller than the dorsal ones; mostly helmet-shaped or saccate; usually with a stylus (this a minute, subulate process or rudimentary sac situated between it and the stem). The vegetative leaves without vittae (but sometimes with discoloured cells (ocelli) scattered or in a median row). Underleaves smaller than the laterals though well developed and conspicuous (usually bilobed, sometimes with a tooth on one or both margins). The cells of the gametophyte with numerous small chloroplasts.
The plants dioecious.
Male inflorescences on short lateral branches, the more or less symmetrical bracts closely imbricate. Male bracts subtending a single antheridium to 2 antheridia. Female inflorescences terminating short lateral branches, rarely on the main axis. Female bracts present (2–5 pairs, asymmetrically bilobed, with entire to laciniate margins, often adnate at their bases to one another and the bracteole). Bracteole present (bilobed, smaller than the associated bracts). Perianth present; extending beyond the bracts, ovoid or obovoid, 3–4 gonous, narrowed abruptly to the beak-like mouth; distally beaked. Calyptra present and well developed (fleshy).
Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule globose. The capsule wall 2 layered (the inner layer with irregular, hyaline, thin cell walls). The capsule dehiscing by four valves (down to about 2/3, being entire at the broad fleshy base). Elaters present (commonly reddish or golden brown); unispirally thickened (according to Pearson and Cooke); remaining attached to the inner walls of the dehiscent capsule valves (orientated vertically in the unopened capsules, wide, with several sessile on the distal half of each valve and having their trumpet-shaped lower ends becoming free at dehiscence).
British representation. 4 species; England, Wales, Scotland, and Ireland.
Classification. Class/Division Hepaticae. Subclass/Class Jungermanniidae. Order Jungermanniales. Family Frullaniaceae.
Illustrations. • F. dilatata: Jameson, in Macvicar (1926). • F. dilatata: Pearson fig. V (1902). • F. dilatata: Pearson fig. V legend. • F. fragilifolia: Jameson, in Macvicar (1926). • F. fragilifolia: Pearson fig. III (1902). • F. fragilifolia, Pearson fig. III legend. • F. germana, Pearson fig. IV (1902). • F. germana, Pearson fig. IV legend. • F. microphylla: Jameson, in Macvicar (1926). • F. microphylla: Pearson fig. II (1902). • legii.jpg. • F. crozalsii: Jameson, in Macvicar (1926). • F. tamariscae: Jameson, in Macvicar (1926). • F. tamariscae: Pearson fig. I (1902). • F. tamarisci, Pearson fig. I legend.
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, 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. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2005 onwards. The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland. Version: 5th August 2019. delta-intkey.com’.
