The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland
Gametophyte. Plants small, green or brownish, never red-tinged, leafy. The shoots prostrate to ascending, simple to sparingly branched. Plants sometimes lacking or confined to female inflorescences. Acrogynous. The leaf cells thin walled, more or less without trigones, or with trigones (then minute but distinct). Rhizoids present; abundant, very pale brown, or colourless.
The leafy shoots dorsiventral, with two equal ranks of lateral leaves and a third, ventral rank of smaller underleaves, or 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 to obliquely inserted; opposite; overlapping; often connate on their dorsal sides, not decurrent, contiguous or slightly connate at the antical bases, succubous; ovate to orbicular, concave, undivided; with vittae (at the leaf bases, where the cells are much elongated). The cells of the gametophyte with numerous small chloroplasts. Gemmae common to rare (on leaf surfaces), or absent.
The plants dioecious.
Male inflorescences intercalary, when dioecious (S. tophacea) with up to 12 pairs of entire, very saccate bracts. Perigynium present and well developed. Marsupia present but vestigial, or absent. Female bracts present (similar to the leaves, but toothed and basally connate with one another and with the perianth). Perianth present (shorter than the bracts to barely emergent, proximally connate with them); the wide mouth lobed or toothed. Calyptra present and well developed (free, tender).
Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule globose to ovoid. Elaters presumably present (?); if present, probably bispirally thickened; free. Ecology. Occurring in basic habitats.
British representation. 2 species; England, Wales, Scotland, and Ireland.
Classification. Class/Division Hepaticae. Subclass/Class Jungermanniidae. Order Jungermanniales. Family Arnelliaceae.
Illustrations. • S. nigrella: 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’.