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

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L. Watson and M. J. Dallwitz

Nardia S.F. Gray

Including Alicularia Corda.

Gametophyte. Plants caespitose, very small to robust, leafy. Sparsely branching ventrally from postical leaf angles. Acrogynous. The leaf cells with trigones, or without trigones. Rhizoids present (usually long and abundant); pale.

The leafy shoots dorsiventral, with two equal ranks of lateral leaves and a third, ventral rank of smaller underleaves. The vegetative leaves obliquely inserted; alternate; overlapping; reniform to orbicular, succubous; undivided to several-lobed (entire, retuse or rarely bilobed); without vittae. Underleaves present but much reduced or vestigial (lanceolate or subulate and usually restricted to the young parts of stems). The cells of the gametophyte with numerous small chloroplasts. The chloroplast-containing cells with conspicuous oil bodies (large, 1-several per cell). Gemmae absent.

The plants dioecious, or bisexual; when bisexual, having the gametangia grouped into bracteate inflorescences; paroecious.

Male inflorescences when dioecious, terminal prior to becoming intercalary, the bracts leaflike but basally saccate. Female inflorescences terminal. Perigynium present and well developed. Female bracts present (2–3 pairs, nearly opposite, similar to but larger than the leaves and sometimes emarginate). Bracteole present (these toothed). Perianth present; very short and not exserted, tender, concrescent with the hollowed out stem apex. Calyptra present and well developed (derived from tjhe perigynium).

Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule more or less globose. The capsule wall 2 layered. The spores unicellular when shed. Elaters present; bispirally thickened.

British representation. 4 species; England, Wales, Scotland, and Ireland.

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

Illustrations. • N. breidleri (as Alicularia): Jameson, in Macvicar (1926). • N. compressa (as Alicularia): Jameson, in Macvicar (1926). • N. compressa: Peason fig. CLX (1902). • N. compressa: Peason fig. CLX legend. • N. geoscyphus: Jameson, in Macvicar (1926). • cf. N. geoscyphus or Marsupella sp.? (as N. sylvrettae): Pearson fig. CLXII (1902). • cf. N. geoscyphus or Marsupella sp.? (as N. sylvrettae): Pearson fig. CLXII legend. • N. scalaris (as Alicularia): Jameson, in Macvicar (1926). • N. scalaris : Pearson fig. CLXI (1902). • N. scalaris : Pearson fig. CLXI 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.’.