The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland

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L. Watson and M. J. Dallwitz

Gymnocolea (Dum.) Dum.

Gametophyte. Plants forming dark green to blackish patches, leafy. Unbranched or branching sparsely from procumbent to erect shoots. Acrogynous. The leaf cells thin walled but with trigones. Rhizoids present; colourless, or brown.

The leafy shoots dorsiventral, with two equal ranks of lateral leaves and a third, ventral rank of smaller underleaves to 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 (as long as wide). The vegetative leaves transversely inserted (G. acutiloba), or obliquely inserted; alternate; overlapping and distant (the lower distant); more or less symmetrical, about as long as wide, succubous. The leaf margins entire; on upper and ascending stems incurved or inflexed; dorsally decurrent, or not or only slightly dorsally decurrent. The vegetative leaves 1/3–1/2 bilobed (the lobes obtuse to rounded, less often acute to sub-acute); not complicate-bilobed; without vittae. Underleaves present but much reduced or vestigial, or absent (when present, few and subulate); not bilobed. The cells of the gametophyte with numerous small chloroplasts. Gemmae usually absent.

The plants dioecious.

Male inflorescences terminal, the 4–6 pairs of transversely inserted, concave bracts in G. inflata similar to but smaller than the leaves. Male bracts subtending a single antheridium. Marsupia absent. Female bracts present (widely spreading, similar to but smaller than or not larger than the leaves). Female bracts smaller than the (upper) leaves to similar in size to the (upper) leaves; perianth present; perianth smooth except at the mouth, initially ovoid, becomming ellipsoid to pyriform after fertilization and contracted at the dentate mouth, exposed by the speading bracts, and when unfertilized sometimes forming deciduous propagules. Perianth distally smooth, not plicate. Perianth not beaked.

Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule ovoid to shortly cylindrical. The spores unicellular when shed. Elaters present (reddish brown); bispirally thickened; free.

British representation. 2 species; England, Wales, Scotland, and Ireland.

Classification. Class/Division Hepaticae. Subclass/Class Jungermanniidae. Order Jungermanniales. Family Lophoziaceae.

Illustrations. • G. inflata: Jameson, in Macvicar (1926). • G. inflata (as Jungermania inflata): Pearson fig. CXXXI (1902). • G. inflata (as Jungermania inflata): Pearson fig. CXXXI legend. • G. inflata var. heterostipa (as Cephalozia heterostipa): Pearson fig. LXIV (1902). • G. inflata var. heterostipa (as Cephalozia heterostipa): Pearson fig. LXIV legend. • G. acutiloba: Jameson, in Macvicar (1926).

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.’.