British ferns (Filicopsida)
Wall Spleenwort, Wall Rue.
Sporophyte. The rhizomes short, creeping; bearing scales (when young, the scales dark, subulate). Plants with no clear distinction into fertile and sterile leaves.
Leaves aggregated terminally; to 3–12(–15) cm long; persistent; compound; complexly divided; bipinnate with conspicuously divided pinnules, or bipinnate with conspicuously divided pinnules to tripinnate with undivided ultimate pinnules (the pinnae 3–5 on each side of the leaf, the pinnules rarely more than 5 and often only 3, usually undivided but the lowermost of them sometimes trisect, the ultimate segments crenate or dentate and varying in shape on different plants). Pinnae 3–5 on each side of the leaf. The petioles about as long as the blades to longer than the blades (up to twice as long, their bases blackish, the rest dull green like the narrowly winged rachis and the rest of the leaf, glandular and with a few hair-like scales when young); vascularised via a single strand (representing fusion of a pair of leaf traces). Leaf blades in outline ovate-triangular, or lanceolate-triangular; leathery. The longest pinnae the lowermost; 1–3 cm long. The venation of the lamina open.
The sporangia superficial; initially aggregated in sori. The sori linear elongated (about 2 mm long, borne along the veins and more or less longitudinally along the segments, two or more); finally becoming confluent when mature; with a true indusium. The indusia attached on one side along a vein; whitish, finally crenulate. Paraphyses absent. The mature spores monolete; with a perispore.
Distribution and habitat. On base-rich substrates. Basic rocks and all kinds of base-rich walls, including mortar in acid regions. Common throughout most of the British Isles.
Vice-county records. Britain: West Cornwall, East Cornwall, South Devon, North Devon, South Somerset, North Somerset, North Wiltshire, South Wiltshire, Dorset, Isle of Wight, South Hampshire, North Hampshire, West Sussex, East Sussex, East Kent, West Kent, Surrey, South Essex, North Essex, Hertfordshire, Middlesex, Berkshire, Oxfordshire, Buckinghamshire, East Suffolk, West Suffolk, East Norfolk, West Norfolk, Cambridgeshire, Bedfordshire, Huntingdonshire, Northamptonshire, East Gloucestershire, West Gloucestershire, Monmouthshire, Herefordshire, Worcestershire, Warwickshire, Staffordshire, Shropshire, Glamorgan, Breconshire, Radnorshire, Carmarthenshire, Pembrokeshire, Cardiganshire, Montgomeryshire, Merionethshire, Caernarvonshire, Denbighshire, Flintshire, Anglesey, South Lincolnshire, North Lincolnshire, Leicestershire, Nottinghamshire, Derbyshire, Cheshire, South Lancashire, West Lancashire, South-east Yorkshire, North-east Yorkshire, South-west Yorkshire, Mid-west Yorkshire, North-west Yorkshire, Durham, South Northumberland, North Northumberland, Westmorland, Cumberland, Isle of Man, Dumfriesshire, Kirkcudbrightshire, Wigtownshire, Ayrshire, Renfrewshire, Lanarkshire, Peeblesshire, Selkirkshire, Roxburghshire, Berwickshire, East Lothian, Midlothian, West Lothian, Fifeshire, Stirlingshire, West Perthshire, Mid Perthshire, East Perthshire, Angus, Kincardineshire, South Aberdeenshire, North Aberdeenshire, Banffshire, Moray, East Inverness-shire, West Inverness-shire, Argyll Main, Dunbartonshire, Clyde Isles, Kintyre, South Ebudes, Mid Ebudes, North Ebudes, West Ross, East Ross, East Sutherland, West Sutherland, Caithness, Outer Hebrides, Orkney islands, Shetland, Channel Islands. Ireland: South Kerry, North Kerry, West Cork, Mid Cork, East Cork, Waterford, South Tipperary, Limerick, Clare, North Tipperary, Kilkenny, Wexford, Carlow, Leix, South-east Galway, West Galway, North-east Galway, Offaly, Kildare, Wicklow, Dublin, Meath, West Meath, Longford, Roscommon, East Mayo, West Mayo, Sligo, Leitrim, Cavan, Louth, Monaghan, Fermanagh, East Donegal, West Donegal, Tyrone, Armagh, Down, Antrim, Londonderry.
Classification. Family Polypodiaceae (C.T.W.); Aspleniaceae (Swale and Hassler); Aspleniaceae (Stace). Order Aspleniales (Swale and Hassler).
A. x murbeckii Dörfl. = A. ruta-muraria x A. septentrionale.
Comments. The base of the petiole blackish, the rest dull green like the narrowly winged rachis and the rest of the leaf.
Illustrations. • A. ruta-muraria: Eng. Bot. 1880 (1886). • A. ruta-muraria: Sowerby and Johnson (1859). • A. x clermontiae (A. ruta-muraria x A. trichomanes): Eng. Bot. 1879 (1886). • 9 British Aspleniaceae (inter alia).
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. 2004 onwards. British ferns (Filicopsida). Version: 4th January 2012. http://delta-intkey.com’.