British ferns (Filicopsida)
D. austriaca auct., D. aristata Druce.
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 (20–)30–150(–180) cm long; (sub-) persistent, or dying in the autumn (decaying from the base upwards); circinnate; compound; complexly divided; bipinnate with conspicuously divided pinnules to tripinnate with undivided ultimate pinnules. Pinnae 15–25 on each side of the leaf. The petioles shorter than the blades (dark brown at the base and pale or green above, with ovate-lanceolate or lanceolate entire scales which are dark brown in the centre and pale brown at their edges, the covering usually dense at the base and less so above); about 0.25–0.7 x the length of the blade (from about 1/4 to 2/3 its length); vascularised by several discrete strands (derived via several leaf traces). Petiolar scales not golden brown (pale only, or dark-centred with pale edges). Leaf blades in outline ovate to ovate-triangular. The longest pinnae the lowermost, or near the base of the blade (the three or more basal pairs of pinnae the longest, about equal in length); 6–20 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; with the basal pinnule on its lower side nearly always less than half as long as the pinna itself. The venation of the lamina open.
The sporangia superficial; protected; aggregated in sori. The sori sub-orbicular (about 0.5–1 mm diameter, in a row down either side of the segment); remaining discrete at maturity; with a true indusium. The indusia reniform and attached at the indentation; fringed with stalked glands, and irregularly toothed. Paraphyses absent. The mature spores dark brown; with dense blunt spinules; monolete.
Distribution and habitat. Woods, hedgebanks, ditches, in shady places on heaths and mountains. Common throughout 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.); Dryopteridaceae (Swale and Hassler); Dryopteridaceae (Stace). Order Dryopteridales (Swale and Hassler).
D. x deweveri (J.T. Jansen) Wacht. = D. carthusiana x D. dilatata; D. x ambrosiae Fraser-Jenk. & Jermy = D. dilatata x D. expansa.
Illustrations. • D. dilatata: Lastrea dilatata, Eng. Bot. 1857 (1886). • D. dilatata: 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’.