| | Ferns (Filicopsida) of Britain and Ireland |
“Forked Spleenwort”.
Sporophyte. The rhizomes short, creeping; bearing scales (when young, the scales dark, subulate).
Leaves aggregated terminally; to 4–15 cm long; persistent; simple; more or less dichotomously divided and 1–2(-3) times forked, the stalked forks often unequal, the segments linear-cuneiform. The petioles about as long as the blades (rarely), or longer than the blades (usually several times as long, their bases blackish, the rest dull green like the rachis and the rest of the leaf, with a few small hairs when young); vascularised via a single strand (representing fusion of a pair of leaf traces). The venation of the lamina open.
The sporangia superficial; ambiguously aggregated in sori. The sori narrowly linear elongated (5–20 mm long, covering almost the whole surface and length of the segment); with a true indusium. The indusia attached on one side along a vein; whitish, entire. The mature spores monolete; with a perispore.
Distribution and habitat. On acid substrates. In rock crevices in acid places, mainly upland. Very local, in western and northern Britain from S Devon to W Ross, also in W Galway.
Vice-county records. Britain: South Devon, North Devon, South Somerset, East Kent, Surrey, Radnorshire, Cardiganshire, Montgomeryshire, Merionethshire, Caernarvonshire, Mid-west Yorkshire, Durham, South Northumberland, North Northumberland, Westmorland, Cumberland, Peeblesshire, Roxburghshire, Midlothian, Fifeshire, East Perthshire, South Aberdeenshire, East Inverness-shire, West Inverness-shire, North Ebudes, West Ross, East Ross, West Sutherland. Ireland: West Galway, Down.
Classification. Family Polypodiaceae (C.T.W.); Aspleniaceae (Swale and Hassler); Aspleniaceae (Stace). Order Aspleniales (Swale and Hassler).
A. x alternifolium Wulfen = A. trichomanes x A. septentrionale; A. x murbeckii Dörfl. = A. ruta-muraria x A. septentrionale.
Illustrations. • A. septentrionale: Eng. Bot. 1882 (1886). • A. septentrionale: Sowerby and Johnson (1859). • A. x alternifolium (A. septentrionale x A. trichomanes): as A. germanicum, Eng. Bot. 1881 (1886). • 9 Aspleniaceae of Britain and Ireland (inter alia). ASPLENIACEAE. 1741, Asplenium adiantum-nigrum; 1742, Asplenium trichomanes; 1743, Asplenium viride; 1744, Asplenium marinum; 1745, Asplenium ruta-muraria; 1746, Aslpenium x-alternifolium (A. septentrionale x A. trichomanes); 1747, Asplenium septentrionale. 1748, Phyllitis scolopendrium. 1749, Ceterach officinarum. Pteridaceae. 1750, Anogramma leptophylla. Blechnaceae. 1751, Blechnum spicant. Hypolepidaceae. 1752, Pteridium aquilinum. Adiantaceae. 1753, Adiantum capillus-veneris. Hymenophyllaceae. 12754. Trichomanes speciosum; 1755, Hymenophyllum tunbrigense; 1756, Hymenophyllum wilsonii. Osmundaceae. 157, Osmunda regalis. Ophioglossaceae. 1758, Botrychium lunaria; 1759, Ophioglossum vulgatum; 1760, Ophioglossum lusitanicum. From Sowerby and Johnson (1863, the family assignments following Swale and Hassler).
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. 2004 onwards. Ferns (Filicopsida) of Britain and Ireland. Version: 5th August 2019. delta-intkey.com’.
