The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland
Gametophyte. Plants forming soft, dark green patches, leafy. The shoots procumbent, irregularly 1–2-pinnately branched, usually with one or two innovations arising immediately below the perianth. The branching of the Frullania type, of the Radula type, and conventional (the vegetative branching both Frullania type and intercalary, the female inflorescences with Radula-type innovations). The stems with cortical cells clearly differentiated from the cells of the central strand (the cortex unistratose). Acrogynous. The leaf cells without trigones.
The leafy shoots dorsiventral, with two equal ranks of lateral leaves and a third, ventral rank of smaller underleaves. The vegetative leaves markedly asymmetrical. The vegetative leaves with J-shaped insertion; alternate; approximate to overlapping; spreading horizontally, incubous; deeply bilobed (almost to the base, conduplicate, the dorsal lobe asymmetrically ovate and apically rounded, not or hardly crossing the stem, without ocelli, the margin entire to spinosely toothed or ciliate, the small ventral lobe variable in form from helmet-shaped and sometimes with a narrow spur-like stylus projecting from the base to lanceolate, acuminate with 0–2 spinose teeth or very small and manifested only as a reflexed tooth at the base of the dorsal lobe); complicate-bilobed. The ventral lobes much smaller than the dorsal ones; mostly helmet-shaped or saccate; sometimes with a stylus. The vegetative leaves without vittae. Underleaves smaller than the laterals though well developed and conspicuous (ovate to orbicular, 1/2–2/3 bilobed, the lobes emarginate, the margins with 0–2 spinose teeth). The cells of the gametophyte with numerous small chloroplasts.
The plants bisexual; having the gametangia grouped into bracteate inflorescences; autoecious.
Male inflorescences on lateral branches that are shorter than to scarcely longer than the leaves, with 3–4 pairs of bilobed, imbricate, saccate bracts. Male bracts subtending a single antheridium to 2 antheridia. Female inflorescences terminating long branches and main axes, often with 1–2 Radula-type innovations. Female bracts present (conduplicate, asymmetrically bilobed, the lobes acuminate, the margins spinose-dentate). Bracteole present (smaller than the bracts, symmetrically bilobed to 1/2, spinose-dentate).
Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. Elaters present; unispirally thickened; remaining attached to the inner walls of the dehiscent capsule valves (less persistent than in Frullania and more numerous, but similarly orientated vertically in the unopened capsules, sessile on the distal half of each valve and with their trumpet-shaped lower ends becoming free at dehiscence).
British representation. 1 species (J. hutchinsii); England, Wales, Scotland, and Ireland.
Classification. Class/Division Hepaticae. Subclass/Class Jungermanniidae. Order Jungermanniales. Family Jubulaceae.
Illustrations. • J. hutchinsiae: Jameson, in Macvicar (1926). • J. hutchinsiae: Pearson (1902). • J. hutchinsiae, Pearson fig. VI legend.
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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. delta-intkey.com’.