British ferns (Filicopsida)


L. Watson and M. J. Dallwitz

Gymnocarpium dryopteris (L.) Newman

“Oak Fern”.

Thelypteris dryopteris (L.) Slosson), Polypodium dryopteris L., Phegopteris connectilis (Michx.) Watt, Phegopteris dryopteris (L.) Fée, etc.

Sporophyte. The rhizomes long, slender; creeping (below ground); bearing scales, or naked (the few, small scales soon lost).

Leaves distributed along the rhizomes; to 20–40 cm long; dying in the autumn; circinnate (the vernation differing in detail from that of Gymnocarpium robertianum, q.v.). The two unfolded basal pinnae and the rest of the blade rolled separately into three small ‘balls’ in the young leaf. Leaves compound; complexly divided; bipinnate with conspicuously divided pinnules to tripinnate with undivided ultimate pinnules (the second pair of pinnae long-stalked). Pinnae 5–10 on each side of the leaf. Leaves conspicuously bent near the junction of rachis and petiole. The petioles much longer than the blades (blackish). Leaf blades in outline glabrous and bright or clear green, ovate-triangular. The longest pinnae the lowermost (these nearly as large as the rest of the blade); 3–15 cm long. The venation of the lamina open.

The sporangia superficial; exposed; aggregated in sori. The sori sub-orbicular (borne in two rows along the segments, rather small but sometimes to nearly 1 mm in diameter); remaining discrete at maturity; naked and neither indusiate nor pseudo-indusiate.

Distribution and habitat. On neutral substrates and on acid substrates. In damp woods and shady rocky places and ravines, often in more or less acid, humus-rich soil. Frequent in N and W Britain south to the Severn-Humber estuaries, rare and scattered SE of that line and in N Ireland. Often found growing near Phegopteris connectilis.

Vice-county records. Britain: West Cornwall, East Cornwall, South Devon, South Somerset, North Somerset, East Kent, North Essex, Hertfordshire, Berkshire, Oxfordshire, Buckinghamshire, West Suffolk, East Norfolk, West Norfolk, Bedfordshire, Northamptonshire, West Gloucestershire, Monmouthshire, Herefordshire, Worcestershire, Warwickshire, Staffordshire, Shropshire, Glamorgan, Breconshire, Radnorshire, Carmarthenshire, Cardiganshire, Montgomeryshire, Merionethshire, Caernarvonshire, Denbighshire, South Lincolnshire, North Lincolnshire, Leicestershire, 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, 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, Shetland. Ireland: Wicklow, Sligo, Leitrim, Fermanagh, Down, Antrim.

Classification. Family Polypodiaceae (C.T.W.); Woodsiaceae (Swale and Hassler); Woodsiaceae (Stace). Order Athyriales (Swale and Hassler).

Illustrations. • G. dryopteris: as Phegopteris dryopteris, Eng. Bot. 1845 (1886). • G. dryopteris: Sowerby and Johnson (1859). • Gymnocarpium spp. and Woodsia spp. (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.’.