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| The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland |
Gametophyte. Plants very slender, gregarious or forming thin patches, extensive tufts or cushions, leafy. The shoots procumbent to erect, unequally pinnate and branching irregularly. Plants with neither flagella nor flagelliform shoots or branches. Acrogynous. The leaf cells without trigones. Rhizoids present (scarce above, numerous below); colourless; of one kind, all smooth.
The leafy shoots radially symmetrical, with three ranks of similar and more or less equal sized leaves, or dorsiventral, with two equal ranks of lateral leaves and a third, ventral rank of smaller underleaves; julaceous. The vegetative leaves transversely inserted; alternate; overlapping (imbricate, appressed); ovate, carinate-concave, deeply bilobed (with acute lobes and narrow sinus); without vittae. Underleaves more or less similar in size to the laterals (scarcely distinguishable from them, but sometimes somewhat smaller). The cells of the gametophyte with numerous small chloroplasts. The chloroplast-containing cells without oil bodies. Gemmae absent.
The plants dioecious (A. julacea), or bisexual (A. juratzkana); having the gametangia grouped into bracteate inflorescences; when bisexual, paroecious (in A. juratzkana the male bracts are larger than the leaves, and located proximally to the female bracts on clavate shoots).
Male inflorescences in A. julacea terminal before becoming intercalary, with bracts similar to the leaves but more concave. Female inflorescences of A. julacea terminating stems or branches. Female bracts present (appressed, bilobed, becoming hyaline above, with denticulae margins). Perianth present; adnate at its base to the bracts, scarcely to half-exserted beyond them, more or less ovoid, somewhat narrowed to the lobed, denticulate mouth. Perianth deeply distally plicate.
Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem (the capsule shortly pedicellate). The capsule globose. The capsule wall 2 layered (the inner layer with semi-annular thickenings). The capsule dehiscing by four valves. The spores unicellular when shed. Elaters present; bispirally thickened; free.
British representation. 2 species; England, Wales, Scotland, and Ireland.
Classification. Class/Division Hepaticae. Subclass/Class Jungermanniidae. Order Jungermanniales. Family Antheliaceae.
Illustrations. • A. julacea: Jameson, in Macvicar (1926). • A. julacea: Pearson fig. XXXIV (1902). • A. julacea: Pearson fig. XXXIV legend. • A. juratzkana: Jameson, in Macvicar (1926). • A. juratzkana: Pearson fig. XXXV (1902). • A. juratzkana: Pearson fig. XXXV 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’.
