British ferns (Filicopsida)
Sporophyte. The rhizomes short, stout; ascending to erect; bearing scales (densely scaly, with broad, soft scales). Plants with no clear distinction into fertile and sterile leaves.
Leaves aggregated terminally; to 15–60(–75) cm long; persistent (finally decaying from the apex downwards); circinnate; compound; complexly divided; tripinnate with conspicuously divided ultimate pinnules (to almost 4-pinnate, the ultimate pinnules lobed to almost pinnate). Pinnae 15–20 on each side of the leaf. The petioles shorter than the blades to about as long as the blades (dark brown throughout, with few or numerous narrow-lanceolate, lacerate, uniformly coloured reddish-brown scales); about 0.5–1 x the length of the blade (more than half as long); vascularised by several discrete strands (derived via several leaf traces). Petiolar scales not golden brown (few, pale). Leaf blades in outline ovate-triangular. The longest pinnae the lowermost; 5–15 cm long. The pinnae not decreasing markedly in length basipetaly, the basal pinnae not or scarcely shorter than the longest pair. The lowest pinna with the lowest pinnule on the lower side much longer than the lowest one on the upper side, and often longer than the one or two adjoining it as well. The venation of the lamina open.
The sporangia superficial; protected; aggregated in sori. The sori sub-orbicular (about 0.5–1 mm in diameter, forming a row down each side of the midrib of the segment); remaining discrete at maturity; with a true indusium. The indusia reniform and attached at the indentation; fringed with sessile glands, and irregularly toothed. Paraphyses present in the sporangia. The mature spores monolete; with a perispore.
Distribution and habitat. Woods, ravines and hedgebanks, in moist shady places. Local in Ireland and W Britain from W Cornwall to the Outer Hebrides and Orkney, scarce in E Britain except frequent in acid habitats in Kent and Sussex.
Vice-county records. Britain: West Cornwall, East Cornwall, South Devon, North Devon, South Somerset, South Wiltshire, Dorset, South Hampshire, West Sussex, East Sussex, East Kent, West Kent, West Gloucestershire, Herefordshire, Shropshire, Glamorgan, Breconshire, Carmarthenshire, Pembrokeshire, Cardiganshire, Montgomeryshire, Merionethshire, Caernarvonshire, Denbighshire, Flintshire, Anglesey, South Lancashire, West Lancashire, North-east Yorkshire, South-west Yorkshire, Mid-west Yorkshire, South Northumberland, Westmorland, Cumberland, Isle of Man, Kirkcudbrightshire, Ayrshire, Renfrewshire, Stirlingshire, West Perthshire, Mid Perthshire, East Perthshire, South Aberdeenshire, North Aberdeenshire, East Inverness-shire, West Inverness-shire, Argyll Main, Dunbartonshire, Clyde Isles, Kintyre, South Ebudes, Mid Ebudes, North Ebudes, West Ross, West Sutherland, Caithness, Outer Hebrides, Orkney 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, Wicklow, 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.); Dryopteridaceae (Swale and Hassler); Dryopteridaceae (Stace). Order Dryopteridales (Swale and Hassler).
D. x pseudoabbreviata Jermy = D. oreades x D. aemula.
Illustrations. • D. aemula: as Lastrea aemula, Eng. Bot. 1858 (1886). • D. aemula: Sowerby and Johnson (1859). • 9 British Dryopteridaceae (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’.