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

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L. Watson and M. J. Dallwitz

Douinia (C. Jens.) Buch.

Gametophyte. Plants olive or bluish green or brownish, leafy. In patches or growing through other bryophytes, shoots procumbent with ascending apices or ascending, the stems sparsely branched. Acrogynous. The leaf cells with trigones, or 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 somewhat or markedly asymmetrical. The vegetative leaves transversely inserted (distichous, concave-conduplicate, not keeled, the margins entire or obscurely toothed); alternate; overlapping to distant (the lower leaves distant); bilobed (to about halfway, the lobes lanceolate and tapering to the acute apices, the dorsal one smaller, narrower and more sharply pointed than the ventral one); complicate-bilobed; leaves not keeled. The ventral lobes larger than the dorsal lobes. The vegetative leaves without vittae; with a waxy cuticle. The cells of the gametophyte with numerous small chloroplasts. Gemmae absent.

The plants dioecious.

Male inflorescences terminal and spicate, becoming intercalary, with 3–6 pairs of imbricate bracts, these smaller and more symmetrical than the leaves, and saccate. Female bracts present (larger and more symmetrical than the leaves, the margins entire or toothed). Perianth present (occasionally to frequently); ovoid, ciliate at the contracted mouth. Perianth distally plicate (deeply so, almost to the base).

Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule globose. The capsule wall 3 layered. The spores unicellular when shed. Elaters present; unispirally thickened, or with annular thickenings; free.

British representation. 1 species (D. ovata); England, Wales, Scotland, and Ireland.

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

Illustrations. • Douinia ovata (as Diplophyllum dicksoni): Pearson fig. C (1902). • Douinia ovata (as Diplophyllum dicksoni): Pearson fig. C legend. • D. ovata (P.L. Redfearn,

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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.’.