The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland
Gametophyte. Plants minute to 1 m long, in small, depressed, reddish-brown patches, leafy. Shoots prostrate, stems branching irregularly, often partly naked by shedding of propagative leaves and underleaves, innovating from below female inflorescences. The branching apical, or ventral and apical (terminal and/or postical-intercalary). The stems with no clear differentiation of cortical and central tissues (the cortical cells slightly wider); not translucent. Plants with neither flagella nor flagelliform shoots or branches. Acrogynous. The leaf cells 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. The vegetative leaves more or less symmetrical (to weakly asymmetrical). The vegetative leaves wedge-shaped; very obliquely inserted, or transversely inserted (or almost so); alternate; distant, or overlapping to distant (seldom locally approximate); thick and brittle, sub-orbicular to ovate or rarely obovate, obdeltoid or obcuneate, the dorsal margin often decurrent, the ventral sometimes connate with the underleaves, succubous (sometimes caducous). The leaf margins not multi-ciliate. The vegetative leaves bluntly, very shallowly bilobed, or undivided (or sometimes obscurely toothed); not complicate-bilobed; leaves not keeled; without vittae. Underleaves much smaller than the laterals though well developed and conspicuous (very variable, usually patent, 1–2-lobed with 1–2 ciliate teeth, or rarely simple); bilobed, or not bilobed. The cells of the gametophyte with numerous small chloroplasts. The chloroplast-containing cells with conspicuous oil bodies (but these raidly fugacious). Gemmae absent (unknown - asexual reproduction via caducous leaves and underleaves).
The plants dioecious; having the gametangia grouped into bracteate inflorescences (but inflorescences very rare).
Male inflorescences lateral and spicate or intercalary or occasionally ventral. Male bracts larger than the leaves. Female inflorescences terminating main axes or branches. Perigynium absent or vestigial. Marsupia absent. Female bracts present. Female bracts similar in size to the (upper) leaves, or similar in size to the (upper) leaves to larger than the (upper) leaves (of similar size to or somewhat larger than the adjacent leaves). Bracteole present (free or connate with one bract). Perianth present; inflated below and laterally compressed above, the mouth truncate, entire to toothed, bilabiate with a rudimentary third lip. Perianth distally smooth, not plicate. Perianth not beaked.
Sporophyte. The sporophyte presumably elevated by elongation of the seta, with no intercalary meristem (but unknown in Europe). The capsule ovoid. The capsule wall 2 layered, or 4–5 layered. Elaters present; free. Ecology. Occurring in neutral pH conditions, or acid conditions; saxicolous, or not saxicolous; not montane. Generally on trunks of deciduous trees and shrubs, sometimes on vertical surfaces of neutral to acid rocks.
British representation. 1 species (L. cuneifoleus); Scotland and Ireland.
Classification. Class/Division Hepaticae. Subclass/Class Jungermanniidae. Order Jungermanniales. Family Geocalycaceae.
Illustrations. • L. cuneifolius: Jameson, in Macvicar (1926). • L. cuneifolius (as Clasmatocolea cuneifolia): Pearson fig. CV (1902). • L. cuneifolius (as Clasmatocolea cuneifolia): Pearson fig. CV 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’.