The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland
Gametophyte. Plants leafy. The stems usually prostrate with ascending apices, flexuose or arcuate, simple or branching ventrally from the postical angles of the leaves, repeatedly innovant from below female inflorescences. Acrogynous. The leaf cells with trigones (small to large), or without trigones. Rhizoids present (usually in ventral tufts); colourless.
The leafy shoots dorsiventral, with the two ranks of laterals more or less equal in size and the ventral rank lacking, or dorsiventral, with two equal ranks of lateral leaves and a third, ventral rank of smaller underleaves and 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 not wedge-shaped; obliquely inserted (and more or less decurrent on the dorsal side, almost semi-amplexicaul); opposite, or alternate; overlapping to distant (the lower), or overlapping (the upper); orbicular or quadrate-orbicular, succubous. The leaf margins entire; dorsally dorsally decurrent. The vegetative leaves undivided, or undivided to bilobed (entire or retuse); not complicate-bilobed. Underleaves present but much reduced or vestigial, or absent (if present, very small and mostly confined to female shoots). The cells of the gametophyte with numerous small chloroplasts. The chloroplast-containing cells with conspicuous oil bodies (7–20 per cell). Gemmae absent.
The plants dioecious.
Male inflorescences terminal before becoming intercalary, with 4–6 pairs of imbricate, ventricose bracts each with an inflated antical lobule subtending the antheridia. Male bracts subtending a single antheridium (usually), or 2 antheridia. The antheridial stalks 2–4 seriate. Female inflorescences terminal. Perigynium absent or vestigial. Female bracts present (one pair, somewhat larger than the leaves, laciniate). Female bracts larger than the (upper) leaves. Bracteole present (large, laciniate). Perianth present; emergent and longly exserted when fertile, and narrowing to the denticulate or ciliate mouth. Perianth distally plicate (deeply 6–10 plicate). Perianth not beaked.
Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule ovoid. The capsule wall 4–5 layered. The spores unicellular when shed. Elaters present; reddish-brown, laxly bispirally thickened; free.
British representation. 2 species; England, Wales, and Scotland.
Classification. Class/Division Hepaticae. Subclass/Class Jungermanniidae. Order Jungermanniales. Family Jungermanniaceae.
Illustrations. • J. autumnalis: Jameson, in Macvicar (1926). • cf. J. autumnalis (as Jungermannia autumnalis): Pearson fig. CXXIX (1902). • cf. J. autumnalis (as Jungermannia autumnalis): Pearson fig. CXXIX legend. • J. undulifolia (as schraderi): Jameson, in Macvicar (1926). • cf. J. undulifolia (as Jungermannia autumnalis var. schraderi): Pearson fig. CXXX (1902). • cf. J. undulifolia (as Jungermannia autumnalis var. schraderi): Pearson fig. CXXX 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’.