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

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L. Watson and M. J. Dallwitz

Nowellia Mitt.

Gametophyte. Plants small or medium sized, green or rosy, leafy. The shoots procumbent, the stems sparingly branching ventrally. The branching conventional. The stems with cortical cells clearly differentiated from the cells of the central strand (the cortex hyaline, the central cylinder opaque). Acrogynous. The leaf cells without trigones.

The leafy shoots dorsiventral, with the two ranks of laterals more or less equal in size and the ventral rank lacking. The vegetative leaves markedly asymmetrical. The vegetative leaves transversely inserted (very narrowly based); alternate; overlapping. The leaf margins toothed, or entire (sometimes with a ventral tooth); not or only slightly dorsally decurrent. The vegetative leaves very concave and asymmetrical, bilobed (having the ventral margin inflexed to form a conspicuous, inflated sac, the long decurved lobes very acuminate); without vittae. The cells of the gametophyte with numerous small chloroplasts. The chloroplast-containing cells without oil bodies. Gemmae rare (at the stem tips, unicellular).

The plants usually dioecious.

Male inflorescences on dwarf ventral branches, or terminating longer branches before becoming intercalary, the bracts bilobed. Male bracts subtending a single antheridium. Female inflorescences on dwarf ventral branches. Perigynium absent or vestigial. Female bracts present (slightly connate basally, larger than the leaves, bilobed, dentate). Bracteole present (similar to the bracts). Perianth present; narrowly ovoid, trigonous above with a wide, ciliate mouth. Calyptra absent.

Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule ovoid. The capsule wall 2 layered. The capsule not green (reddish brown). The spores unicellular when shed. Elaters present; bispirally thickened; free (?).

British representation. 1 species (N. curvifolia); England, Wales, Scotland, and Ireland.

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

Illustrations. • N. curvifolia: Jameson, in Macvicar (1926). • Nowellia curvifolia (as Cephalozia): Pearson fig. LXI (1902). • Nowellia curvifolia (as Cephalozia): Pearson fig. LXI 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.’.