British ferns (Filicopsida)


L. Watson and M. J. Dallwitz

Dryopteris affinis (Lowe) Fraser-Jenkins

“Scaly Male Fern”.

Including Dryopteris borreri Newman, D. pseudomas (Woll.) Holub & Pouzar, D. affinis (Lowe) Fraser-Jenkins subsp. borreri; ~ D. filix-mas.

Sporophyte. The rhizomes short, stout; more or less erect; bearing scales (densely scaly, with broad, soft scales).

Leaves aggregated terminally (crowns solitary or few); not rooting at their tips; to (25–)50–150(–180) cm long (usually over 50 cm); usually persistent; circinnate; compound; complexly divided; once pinnate, with conspicuously divided pinnae, or bipinnate with more or less undivided pinnules to bipinnate with conspicuously divided pinnules (when bipinnate, with ultimate pinnules lobed no more than halfway to the middle). Pinnae 20–35 on each side of the leaf. The petioles shorter than the blades (sparsely or moderately covered with uniformly orange-brown scales, the larger of these lanceolate); about 0.1–1.25(–1.4) x the length of the blade (up to 1/3 but usually less than a quarter as long); vascularised by several discrete strands (derived via several leaf traces). Petiolar scales golden brown and often dark centred, dense. The longest pinnae around the middle of the blade; 5–15 cm long (the pinnae decreasing in length markedly basipetally, the lowest less than to more than half the length of the longest). The pinnae decreasing markedly in length towards the base of the blade, the basal ones relatively short. The bases of the pinnae with a dark brown or blackish blotch above, at the junction with the rachis. The lowest pinna with the lowest 3 or 4 pinnules on either side all about equal in length, or 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; nearly always 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 (usually smaller than in D. filix-mas (q.v.), borne (3-)4–5 on each side of the midrib of the largest pinnules, and at least 3 on the majority); remaining discrete at maturity; with a true indusium. The indusia reniform and attached at the indentation; entire, not glandular, embracing the sporangium when young. Paraphyses absent. The mature spores monolete; without a perispore.

Distribution and habitat. On neutral substrates to on acid substrates (?). Seemingly widespread in 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).

The apogamous D. remota (Braun ex Döll) Druce = D. affinis x D. expansa; D. x complexa Fraser-Jenk. = D. affinis x D. filix-mas.

Comments. This description may under-estimate variation, being based mainly on subsp. borreri, which seems to be the most widespread of the sub-species.

Illustrations. • 9 other 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.’.