The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland
Gametophyte. Plants small to medium sized, leafy. The shoots prostrate to erect, the stems irregularly branching ventrally from the axils of the underleaves, the fertile branches very small and concealed under the lateral leaves. The branching ventral; conventional. Acrogynous. The leaf cells without trigones. Rhizoids present.
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 markedly asymmetrical. The vegetative leaves not wedge-shaped; more or less obliquely inserted; alternate; overlapping; succubous. The leaf margins entire; flat; dorsally decurrent. The vegetative leaves more or less ovate, undivided to bilobed (bilobed to 1/3 or the apices retuse or emarginate); not complicate-bilobed; without vittae. Underleaves much smaller than the laterals though well developed and conspicuous (simple, ovate-lanceolate to lanceolate, apically entire or notched, the margins toothed or entire basally joined to the adjacent lateral leaf); bilobed to not bilobed. The cells of the gametophyte with numerous small chloroplasts.
The plants dioecious.
Male inflorescences terminal, spicate, very small and concealed under the lateral leaves, with 2–5 pairs or imbricate, very concave, bilobed bracts. Male bracts subtending a single antheridium to 2 antheridia. Perigynium present and well developed (free only near its apex, being concrescent with 2/3 of the length of the perianth, the whole forming a fleshy, ovoid structure protecting the sporophyte). Marsupia absent. Female bracts present (concave, 2–3 lobed). Female bracts much smaller than the (upper) leaves. Bracteole present (resembling the cauline leaves). Perianth present; short, narrowed at the lobed and/or crenulate mouth. Perianth distally smooth, not plicate. Perianth not beaked.
Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule rather long-pedicelled, ovoid. The capsule wall 2 layered (the inner layer with semi-annular thickenings). The capsule brown, not green; dehiscing by four valves. Elaters present; bispirally thickened; free.
British representation. 2 species; England, Wales, Scotland, and Ireland.
Classification. Class/Division Hepaticae. Subclass/Class Jungermanniidae. Order Jungermanniales. Family Geocalycaceae.
Comments. Macvicar's description interprets the perigynium as a calyptra. Illustrations. • H. flotovianus: Jameson, in Macvicar (1926). • H. flotovianus (as H. flotowii):Pearson fig. CVIII (1902). • H. flotovianus (as H. flotowii):Pearson fig. CVIII legend. • H. scutatus: Jameson, in Macvicar (1926). • H. scutatus: Pearson fig. CVII (1902). • H. scutatus: Pearson fig. CVII legend.
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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’.