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

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L. Watson and M. J. Dallwitz

Cephalozia (Dum.) Dum.

Gametophyte. Plants slender and pale, yellowish, dull or bright green or brownish, leafy. The shoots procumbent and stems irregularly branched from the ventral side. The branching ventral. The stems with cortical cells clearly differentiated from the cells of the central strand (the cortex comprising a single layer of large, pellucid cells, through wich the the smaller, thick-walled cells of the central strand are readily visible via transmitted light). Plants with flagella or flagelliform shoots or branches (sometimes, e.g. in Section Cephalozia, arising ventrally), or with neither flagella nor flagelliform shoots or branches. Acrogynous. The leaf cells thin- to thick-walled, without trigones. Rhizoids present.

The leafy shoots dorsiventral, with two equal ranks of lateral leaves and a third, ventral rank of smaller underleaves, or 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. The vegetative leaves transversely inserted to obliquely inserted (to almost longitudinally); overlapping to distant; when overlapping, succubous. The leaf margins entire; deflexed (or at least, leves usually concave); dorsally decurrent to not or only slightly dorsally decurrent. The vegetative leaves spreading horizontally to dorsally secund, orbicular to ovate-quadrate, not or only slightly asymmetrical, usually concave, the ventral margin not inflexed, a third to two thirds bilobed (the lobes often unequal); without vittae. Underleaves present but much reduced or vestigial, or absent (absent, or present but small and subulate only on fertile stems). The cells of the gametophyte with numerous small chloroplasts. Gemmae common to rare (unicellular, at the tips of ascending stems and branches), or absent.

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

Male inflorescences terminal on short or long ventral branches, spicate, sometimes becoming intercalary, the bracts few to many, bilobed, with entire margins or sometimes with a single tooth on the dorsal one. Female inflorescences terminating short or rarely long ventral branches. Female bracts present (much larger than the leaves, 2–5 lobed, the margins sometimes toothed). Bracteole present (similar to or narrower than the bracts, free or basally connate with them). Perianth present; narrowly ovoid, ellipsoid or fusiform-cylindrical, trigonous above, the mouth crenate-dentate to ciliate, the wall 1–3 stratose. Perianth distally smooth, not plicate.

Sporophyte. The sporophyte long-pedicellate, elevated by elongation of the seta, with no intercalary meristem. The capsule wall (1–)2(–3) layered (the inner layer with semi-annular thickenings). The capsule dehiscing by four valves (these straight). The spores unicellular when shed. Elaters present; bispirally thickened; free.

British representation. 10 species; England, Wales, Scotland, and Ireland.

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

Illustrations. • C. ambigua: Jameson, in Macvicar (1926). • C. bicuspidata: Jameson, in Macvicar (1926). • C. bicuspidata: Pearson fig. LVII (1902). • C. bicuspidata: Pearson fig. LVII legend. • C. bicuspidata var. lammersiana (as C. lammersiana): Pearson fig. LVIII (1902). • C. bicuspidata var. lammersiana (as C. lammersiana): Pearson fig. LVIII legend. • C. catenulata: Jameson, in Macvicar (1926). • C. catenulata: Pearson fig. LIV (1902). • C. catenulata: Pearson fig. LIV legend. • C. connivens: Jameson, in Macvicar (1926). • C. connivens: Pearson fig. LX (1902). • C. connivens: Pearson fig. LX legend. • C. hibernica: Jameson, in Macvicar (1926). • C. hibernica: Pearson fig. LIX (1902). • C. hibernica: Pearson fig. LIX legend. • C. leucantha: Jameson, in Macvicar (1926). • C. leucantha: Pearson fig. LXXII (1902). • C. leucantha: Pearson fig. LXXII legend. • C. loitlesbergeri: Jameson, in Macvicar (1926). • C. lunulifolia: Jameson, in Macvicar (1926). • C. lunulifolia: Pearson fig. LVI (1902). • C. lunulifolia: Pearson fig. LVI legend. • cf. C. lunulifolia (as C. pallida): Pearson fig. LV (1902). • cf. C. lunulifolia (as C. pallida): Pearson fig. LV legend. • C. macrostachya: Jameson, in Macvicar (1926). • C. pleniceps: Jameson, in Macvicar (1926).

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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.’.