The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland
Gametophyte. Plants minute to large, reddish-yellow or purple, leafy. With erect or procumbent stems, sometimes branching from the postical angles of the leaves. The branching conventional. Acrogynous. The leaf cells with trigones, or without trigones. Rhizoids present (scarce); colourless; of one kind, all smooth.
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 symmetrical to markedly asymmetrical. The vegetative leaves antically secund, being sub-transversely inserted, the dorsal half more or less transverse, the ventral half oblique; alternate; very concave with inflexed margins or canaliculate, more or less succubous. The leaf margins entire; incurved or inflexed. The vegetative leaves undivided to bilobed (notched to bilobed to 1/2, often with the ventral side larger and more concave, dorsally decurrent or not); without vittae. Underleaves present but much reduced or vestigial, or absent (when present, rudimentary). The cells of the gametophyte with numerous small chloroplasts. Gemmae common to rare (reddish and angular), or absent.
The plants dioecious.
Male inflorescences terminal or intercalary, the few to 12 pairs of imbricate bracts similar to the leaves but basally saccate. Male bracts subtending a single antheridium to several antheridia (1–4). Female inflorescences terminal. Female bracts present (2–4 lobed, entire to toothed, somewhat larger than the leaves). Perianth present; often somewhat flattened dorsiventrally, with a laciniate, lobed or denticulate mouth, free from the bracts. Perianth distally plicate.
Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule shortly pedicellate, ovoid. The capsule wall 2–5 layered (the outer layer with nodulose thickenings, the inner with semi-annular thickenings). The capsule dehiscing by four valves (these sometimes bifid). The spores unicellular when shed. Elaters present; probably bispirally thickened.
British representation. 5 species; England, Wales, Scotland, and Ireland.
Classification. Class/Division Hepaticae. Subclass/Class Jungermanniidae. Order Jungermanniales. Family Lophoziaceae.
Illustrations. • A. donianum: Jameson, in Macvicar (1926). • A. donianum (as Jungermania): Peason fig. CLVII (1902). • A. donianum (as Jungermania): Peason fig. CLVII legend. • A. hellerianum (as Jungermania): Pearson fig. CLII (1902). • A. hellerianum (as Jungermania): Pearson fig. CLII legend. • A. jorgensenii: Jameson, in Macvicar (1926). • A. minutum (as Jungermania): Pearson fig. CLIII (1902). • A. minutum (as Jungermania): Pearson fig. CLIII legend. • A. saxicolum (as Jungeremania): Pearson fig. CLIV (1902). • A. saxicolum (as Jungeremania): Pearson fig. CLIV 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’.