The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland
~ Sphenolobus, Cephaloziella, Cephaloziopsis.
Gametophyte. Plants minute, forming reddish-green to reddish-brown patches, rarely green, leafy. The shoots very slender, procumbent and simple or branching dichotomously and laterally, sometimes with erect, capitate inflorescences in males and innovating from below inflorescences in females. The branching dichotomous. Acrogynous. The leaf cells without trigones. Rhizoids present (but scarce); long and colourless, towards stem apices.
The leafy shoots dorsiventral, with two equal ranks of lateral leaves and a third, ventral rank of smaller underleaves to dorsiventral, with the two ranks of laterals more or less equal in size and the ventral rank lacking. The vegetative leaves more or less symmetrical. The vegetative leaves more or less transversely inserted (about as long to 1.5 times as long as wide, similarly sized throughout and symmetrical, conduplicate-concave with inflexed apices); alternate; overlapping to distant; about 2/3 to 3/4 bilobed (the narrow sinus obtuse to rounded, the acute to acuminate, equal to sub-equal lobes occasionally toothed near the base of the dorsal margin); without vittae. Underleaves present but much reduced or vestigial, or absent (rare, when present small and subulate). The cells of the gametophyte with numerous small chloroplasts. Gemmae absent.
The plants dioecious.
Male inflorescences terminal and capitate before becoming intercalary, the imbricate, very concave, acutely bilobed bracts much larger than the leaves. Male bracts subtending a single antheridium (these roundish). Female inflorescences small capitate heads. Female bracts present (much larger than the leaves, simple or 2–3 lobed, bluntly toothed).
Sporophyte. The sporophyte not known, at least in Britain,. Elaters probably present (not mentioned by the authorities consulted); probably bispirally thickened; free.
British representation. 1 species (S. pearsonii); England, Wales, Scotland, and Ireland.
Classification. Class/Division Hepaticae. Subclass/Class Jungermanniidae. Order Jungermanniales. Family Lophoziaceae.
Illustrations. • S. pearsonii: Jameson, in Macvicar (1926). • S. pearsonii (as Jungermania): Peason fig. CLVI (1902). • S. pearsonii (as Jungermania): Peason fig. CLVI 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. delta-intkey.com’.