British ferns (Filicopsida)


L. Watson and M. J. Dallwitz

Oreopteris limbosperma (All.) Holub

“Mountain Fern”.

Thelypteris limbosperma (All.) H.P. Fuchs, Dryopteris oreopteris (Ehrh.) Maxon, Aspidium oreopteris (Ehrh.) Sw., Thelypteris oreopteris (Ehrh.) Slosson, Lastrea montana Newm., etc.

Sporophyte. The rhizomes short, stout; ascending; bearing scales (when young, with brown lanceolate scales).

Leaves aggregated terminally; to 40–100(–120) cm long; dying in the autumn; complexly divided; once pinnate, with conspicuously divided pinnae (the pinnae scarcely stalked). Pinnae about 20–30 on each side of the leaf. The petioles shorter than the blades (up to a quarter its length, rather stout, sparsely clothed with pale brown, ovate or ovate-lanceolate scales which are most numerous below); vascularised via a single strand. Leaf blades in outline oblanceolate; faintly lemon-scented when crushed (and with numerous sessile glands abaxially). The longest pinnae around the middle of the blade (the pinnae decreasing markedly in length basipetally); 5–12 cm long. The pinnae decreasing markedly in length towards the base of the blade, the basal ones relatively short (the lowest pair much less than half as long as the longest pair). The venation of the lamina open.

The sporangia superficial; exposed; aggregated in sori. The sori sub-orbicular (borne close to the margins of the segment, very small, 0.5 mm or less in diameter); remaining discrete at maturity; with a true indusium, or naked and neither indusiate nor pseudo-indusiate (the indusia either fugaceous and soon lost, or lacking altogether). The indusia when present, perhaps reniform and attached at the indentation (but small, thin, irregularly toothed). Paraphyses present in the sporangia. The mature spores monolete; without a perispore.

Distribution and habitat. On acid substrates. On acid soils in damp, shady places and woods. With a similar distribution to Phegopteris connectilis (q.v.) in western and northern Britain, but commoner, and also frequent in SW and SE England.

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. Ireland: South Kerry, North Kerry, West Cork, Waterford, South Tipperary, Limerick, Clare, North Tipperary, Kilkenny, Wexford, Carlow, Leix, West Galway, Offaly, Wicklow, Dublin, Meath, Longford, Roscommon, West Mayo, Sligo, Leitrim, Cavan, Louth, Fermanagh, East Donegal, West Donegal, Tyrone, Armagh, Down, Antrim, Londonderry.

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

Illustrations. • O. limbosperma: Sowerby and Johnson (1859). • O. limbosperma(?): as Lastrea oreopteris, Eng. Bot. 1849 (1886). • British Thelypteridaceae (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.’.