The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland
Gametophyte. Plants comprising light green patches or scattered shoots, leafy. The shoots prostrate, 1–2 cm long, usually simple apart from innovations below female inflorescences. Acrogynous. Rhizoids present; pale reddish or colourless to violet or purple.
The leafy shoots dorsiventral, with the two ranks of laterals more or less equal in size and the ventral rank lacking. The vegetative leaves more or less transversely inserted (patent, often connate on their dorsal sides); opposite; overlapping; ovate to ovate-orbicular, undivided; with vittae (at the leaf bases, where the cells are much elongated). The cells of the gametophyte with numerous small chloroplasts. Gemmae absent (reproducing vegetatively by axillary buds).
The plants dioecious.
Male inflorescences not known in Britain: intercalary, with saccate, distally recurved bracts in few pairs. Male bracts subtending a single antheridium to 2 antheridia. Female inflorescences on the dorsal side of the stem apex, the archegonia surrounded by scales in a depression. Perigynium present and well developed (marsupial). Marsupia present as downgrowths from stem apices, surrounding the developing sporophytes and carrying them into the substrate (this cylindrical, fleshy, pendulous, with rhizoids). Female bracts present (entire, similar to but larger than the leaves). Perianth present.
Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule long pedicellate, shortly cylindrical. The capsule wall 2 layered. The capsule dehiscing by four valves (divided to the base). The spores unicellular when shed. Elaters present; short, laxly bispirally thickened; short, free. Ecology. Occurring in neutral pH conditions, or acid conditions (calcifuge).
British representation. 1 species (G. ericetorum); England.
Classification. Class/Division Hepaticae. Subclass/Class Jungermanniidae. Order Jungermanniales. Family Arnelliaceae.
Illustrations. • G. ericetorum: Jameson, in Macvicar (1926).
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. delta-intkey.com’.