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

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L. Watson and M. J. Dallwitz

Radula Dum.

Gametophyte. Plants mostly medium sized to large and forming thin patches, yellowish- to olive-green or brown, leafy. The shoots prostrate, sparingly 1–2 pinnate, the branching lateral. The branching terminal of the Radula type. Acrogynous. The leaf cells with trigones, or without trigones. Rhizoids present (confined to the inflated parts of ventral leaf lobes, near the keel).

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 not wedge-shaped; with J-shaped insertion; alternate; overlapping (approximate to imbricate); spreading horizontally, incubous. The leaf margins entire. The vegetative leaves conduplicate- bilobed (the ventral lobe smaller than the dorsal one, the margins entire, the keel region inflated); complicate-bilobed; leaves keeled proximally to the lobes. The ventral lobes much smaller than the dorsal ones; without a stylus. The vegetative leaves without vittae. The cells of the gametophyte with numerous small chloroplasts. The chloroplast-containing cells with conspicuous oil bodies (1–3 per cell, and so large as to render the cells opaque). Gemmae or caducous leaves common, or rare, or absent.

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

Male inflorescences in dioecious species - i.e. mostly - terminal, spicate, with few to many imbricate, erect, saccate bracts smaller than the leaves; in monoecious species comprising fewer bracts which are saccate but otherwise more or less similar to the vegetative leaves, subtending 1–2 or rarely 3 antheridia. Male bracts subtending a single antheridium to 2 antheridia, or several antheridia (rarely 3). Female bracts present (usually two, smaller than the vegetative leaves and with a relatively larger ventral lobe). Perianth present; proximally terete and dorsiventrally compressed distally, smooth, the wide mouth entire to dentate. Perianth distally smooth, not plicate.

Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule shortly and stoutly pedicellate, ovoid to shortly cylindrical. The capsule wall 2 layered. The capsule dehiscing by four valves (to the base). The spores unicellular when shed. Elaters present; long, slender, obtuse, closely bispirally thickened; free.

British representation. 6 species; England, Wales, Scotland, and Ireland.

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

Illustrations. • R. aquilegia: Jameson, in Macvicar (1926). • R. aquilegia: Pearson fig. XXV (1902). • R. aquilegia: Pearson fig. XXV, legend. • R. carringtonii: Jameson, in Macvicar (1926). • R. carringtonii: Pearson fig. XXVI (1902). • R. carringtonii: Pearson fig. XXVI legend. • R. complanata: Jameson, in Macvicar (1926). • R. complanata: Pearson fig. XXVII (1902). • R. complanta: Pearson fig. XXVII legend. • R. holtii: Jameson, in Macvicar (1926). • R. holtii: Pearson fig. XXIV (1902). • R. holtii: Pearson fig. XXIV legend. • R. lindbergiana: Jameson, in Macvicar (1926). • cf. R. lindbergiana (as lindbergii): Pearson fig. XXII (1902). • R. lindbergii, Pearson fig. XII legend. • cf. R. lindbergiana var. germana: Pearson fig. XXIII, 1902. • legXXIII.jpg<@subject. • R.. • lindbergiana. • var.. • germana:. • Pearson. • fig.. • XXIII. • legend>. • R. voluta: Jameson, in Macvicar (1926). • R. voluta: Pearson fig. XXI (1902). • R. voluta: Pearson fig. XXI, 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.’.