The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland
Gametophyte. Plants small, yellow or yellowish-green, leafy. The branching of the Lejeunea type. The stems with cortical cells clearly differentiated from the cells of the central strand (transverse sections showing 7 cortical cells and 5–25 central cells). Acrogynous. The leaf cells with trigones (scarce, short to medium sized).
The leafy shoots dorsiventral, with two equal ranks of lateral leaves and a third, ventral rank of smaller underleaves. The vegetative leaves with J-shaped insertion; alternate; overlapping to distant (to subimbricate); spreading, oblique, falcate and deflexed, incubous; bilobed (almost to the base, 4–6 cells wide at their bases, with 2–5 ocelli present near the base of each, the dorsal lobe obliquely ovate and subfalcate with a deflexed, acute or subacute apex margins entire, crenulate or serrulate, the the ventral lobe only about half as long, borne more or less at right angles to the free margin of the dorsal one, strongly inflated, the apex a single-celled tooth); complicate-bilobed. The ventral lobes much smaller than the dorsal ones; without a stylus. The vegetative leaves with vittae. Underleaves smaller than the laterals though well developed and conspicuous (distant and only half the number of the lateral leaves, short, obdeltoid or obcordate, bilobed to 1/3 or more with the rounded apices divergent); bilobed. The lobes widely divergent; rounded, 4–6 cells wide at their bases. The cells of the gametophyte with numerous small chloroplasts. The chloroplast-containing cells with conspicuous oil bodies (4–6 per cell, compound). Gemmae absent.
The plants dioecious.
Male inflorescences occupying short branches the imbricate, unequally bilobed bracts in 1–2 pairs, the antical lobe oval and blunt, the postical one similar but smaller. Female inflorescences terminal on a long or short branch, usually with a single simple innovation. Female bracts present (larger than the leaves, complicate, unequally bilobed, the postical one bnarrower and shorter). Bracteole present (more or less free from the bracts, obovate-cuneate, 1/4-bilobed). Perianth present; obovoid or obovoid-clavate, sharply 5-keeled distally, not compressed.
Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. Elaters present; unispirally thickened; persistent on elaterophores (orientated vertically in the unopened capsules and extending to the floor, remaining attached by their upper ends to the inner walls of the distal ends of the dehiscing capsule valves and their trumpet-shaped lower ends becoming free).
British representation. 1 species (H. ovata); England, Wales, Scotland, and Ireland.
Classification. Class/Division Hepaticae. Subclass/Class Jungermanniidae. Order Jungermanniales. Family Lejeuneaceae.
Illustrations. • H. ovata: Jameson, in Macvicar (1926). • H. ovata (as Lejeunea): Pearson fig. VIII (1902). • H. ovata: Pearson fig. VIII 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’.