| | The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland |
Gametophyte. Plants mall to medium sized, in patches, turfs or scattered, leafy. Stems prostrate to ascending from the creeping rhizome, the sparse branching lateral. The branching lateral. The stems with cortical cells clearly differentiated from the cells of the central strand, or with cortical cells clearly differentiated from the cells of the central strand to with no clear differentiation of cortical and central tissues. 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 transversely inserted; overlapping to distant. The leaf margins dorsally decurrent, or not or only slightly dorsally decurrent. The vegetative leaves deeply bilobed (the lobes ovate, blunt, conduplicate, usually with denticulate margins, the dorsal one similar to the ventral but shorter); complicate-bilobed (and keeled, typically cultriform or sub-falcate); leaves keeled proximally to the lobes. The ventral lobes more or less lingulate and parallel-sided, larger than the dorsal lobes (the dorsals partly lying on them). The vegetative leaves with vittae (in the lobes), or without vittae; without a waxy cuticle. The cells of the gametophyte with numerous small chloroplasts. The chloroplast-containing cells with conspicuous oil bodies (2–16 per cell). Gemmae common to absent (when present, unicellular and bluntly stellate).
The plants dioecious, or bisexual; when bisexual, having the gametangia grouped into bracteate inflorescences; in D. obtusifolium, autoecious, or paroecious.
Male inflorescences when dioecious, terminal and spicate, becoming intercalary, the 3–8 or more pairs of imbricate, saccate bracts similar to the leaves or smaller and more symmetrical. Male bracts subtending 2 antheridia, or several antheridia (2–3). The antheridia not mixed with paraphyses. Female bracts present. Perianth present; more or less ovoid, slightly to strongly dorsiventrally compressed, narrowed to the small denticulate mouth. Perianth distally plicate.
Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule longly pedicellate, ovoid. The capsule wall 2 layered (according to Macvicar, the inner layer with semi-annular thickenings), or 4 layered (according to Smith). Elaters present; bispirally thickened; free.
British representation. 3 species; England, Wales, Scotland, and Ireland.
Classification. Class/Division Hepaticae. Subclass/Class Jungermanniidae. Order Jungermanniales. Family Scapaniaceae.
Illustrations. • D. albicans: Jameson, in Macvicar (1926). • D. albicans: Pearson fig. XCVII (1902). • D. albicans: Pearson fig. XCVII legend. • D. gymnostomophila: Jameson, in Macvicar (1926). • D. obtusifolium: Jameson, in Macvicar (1926). • D. obtusifolum: Pearson fig. XCIX (1902). • D. obtusifolum: Pearson fig. XCIX legend. • D. taxifolium: Jameson, in Macvicar (1926). • D. taxifoilium: Pearson fig. XCVIII (1902). • D. taxifoilium: Pearson fig. XCVIII legend.
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, 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. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2005 onwards. The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland. Version: 5th August 2019. delta-intkey.com’.
