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

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L. Watson and M. J. Dallwitz

Scapania (Dum.) Dum.

Gametophyte. Plants small to robust, pale green to deep reddish-nrown or purple, leafy. The shoots prostrate to erect, arising from creeping rhizomatous stems, the branching sparse and lateral. The stems with cortical cells clearly differentiated from the cells of the central strand, or with no clear differentiation of cortical and central tissues. 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 markedly asymmetrical. The vegetative leaves transversely inserted to obliquely inserted, or with J-shaped insertion; alternate; overlapping; distichous, decurrent or not, spreading, usually keeled with the keel sometimes winged, the cuticle smooth to very coarsely papillose, the margins entire or ciliate succubous. The leaf margins denticulate or toothed (usually), or entire; multi-ciliate (S. nimbosa), or not multi-ciliate; incurved or inflexed, or flat. The vegetative leaves 1/2–2/3 or rarely completely bilobed (conduplicate, the lobes long-decurrent to not decurrent, the dorsal one usually smaller than the ventral); complicate-bilobed; leaves usually keeled proximally to the lobes. The ventral lobes larger than the dorsal lobes. The vegetative leaves without vittae. The cells of the gametophyte with numerous small chloroplasts. The chloroplast-containing cells often with conspicuous oil bodies (1–12 per cell). Gemmae common (often, on the margins and lobe tips of upper leaves), or rare to absent; 1–2 celled, ellipsoid, ovoid, pyriform or rounded.

The plants dioecious (nearly always), or bisexual; having the gametangia grouped into bracteate inflorescences; sometimes, in S. compacta, autoecious, or paroecious.

Male inflorescences terminal or becoming intercalary, the several pairs of bracts similar to or smaller than the leaves, basally saccate, subtending 2–7 antheridia mixed with paraphyses. Male bracts subtending 2 antheridia to several antheridia (2–7). The antheridia mixed with paraphyses. Female inflorescences terminal. Female bracts present (these usually larger, more equally lobed and more strongly toothed or ciliate than the leaves). Perianth present; usually frontally compressed, often deflexed, usually truncate with a wide, entire to dentate or ciliate mouth, but rarely subterete and narrowed to the mouth. Perianth distally plicate.

Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule long exserted, ovoid. The capsule wall 3–7 layered (the inner layer with annular thickenings). The spores unicellular when shed. Elaters present; bispirally thickened; free (?).

British representation. 23 species; England, Wales, Scotland, and Ireland.

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

Illustrations. • S. aequiloba: Jameson, in Macvicar (1926). • pears083.gif. • legLXXXIII.jpg. • S. aspera: Jameson, in Macvicar (1926). • S. aspera: Pearson fig. LXXXIV (1902). • S. aspera: Pearson fig. LXXXIV legend. • S. calcicola: Jameson, in Macvicar (1926). • S. compacta: Jameson, in Macvicar (1926). • S. compacta: Pearson fig. LXXX (1902). • S. compacta Pearson fig. LXXX legend. • S. compacta (as resupinata): Pearson fig. LXXXV (1902). • S. compacta (as resupinata): Pearson fig. LXXXV legend. • S. curta: Pearson fig. XCV (1902). • S. curta: Pearson fig. XCV legend. • cf. S. curta (as S. rosacea): Pearson fig. XCIV (1902). • cf. S. curta (as S. rosacea): Pearson fig. XCIV legend. • S. cuspiduligera: Jameson, in Macvicar (1926). • S. cuspiduligera (as bartlingii): Pearson fig. LXXXI (1902). • S. cuspiduligera (as bartlingii): Pearson fig. LXXXI legend. • S. gracilis: Jameson, in Macvicar (1926). • S. irrigua: Jameson, in Macvicar (1926). • S. irrigua: Pearson fig. XCII (1902). • S. irrigua: Pearson fig. XCII (1902). • S. nemorea (as nemorosa): Jameson, in Macvicar (1926). • S. nemorea (as nemorosa): Pearson fig. LXXXVIII (1902). • S. nemorea (as nemorosa): Pearson fig. LXXXVIII legend. • S. nimbosa: Pearson fig. LXXXVII (1902). • S. nimbosa: Pearson fig. LXXXVII legend. • S. ornithopodioides: Pearson fig. LXXXVI (1902). • S. ornithopodioides: Pearson fig. LXXXVI legend. • S. subalpina: Jameson, in Macvicar (1926). • S. subalpina: Pearson fig. LXXXII (1902). • S. subalpina: Pearson fig. LXXXII legend. • S. uliginosa: Jameson, in Macvicar (1926). • S. uliginosa (as obliqua) Jameson, in Macvicar (1926). • S. uliginosa: Pearson fig. XCIII (1902). • S. uliginosa: Pearson fig. XCIII legend. • S. umbrosa: Pearson fig. XCVI (1902). • S. umbrosa: Pearson fig. XCVI legend. • S. undulata: Pearson fig. LXXXIX (1902). • S. undulata: Pearson fig. LXXXIX legend. • S. undulata (as S. intermedia): Pearson fig. XCI (1902). • S. undulata (as S. intermedia): Pearson fig. XCI legend. • cf. S. undulata (as purpurascens): Pearson fig. XC (1902). • cf. S. undulata (as purpurascens): Pearson fig. XC 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.’.