British ferns (Filicopsida)
Sporophyte. The rhizomes short, ascending, or erect; naked. Plants with no clear distinction into fertile and sterile leaves (but hard to interpret as such: usually bearing only a single leaf comprising two components, the lower sterile and laminate, the upper fertile, branching and non-laminate - see below), or bearing markedly different fertile and sterile leaves (the fertile leaf sometimes accompanied by one or two sterile blades).
Leaves to (2–)5–15(–30) cm long; not circinnate; compound (each usually comprising a green, pinnate, sterile blade below, and a branched fertile pinna above); if correctly interpreted, complexly divided. The fertile leaves having the appearance of a stem with a terminal fertile portion and a single lateral leaf, but actually comprising two pinnae, the upper fertile, stalked and non-laminate, the lower sterile, sessile, and laminate. The sterile green blades 2–12 cm long; pinnate. The fertile spikes 1–5 cm long; branched. The venation of the lamina open.
Eusporangiate. The sporangia all alike, relatively massive, sub-sessile in two rows on the branches of the fertile component of the leaf; marginal (in origin); exposed; not aggregated into sori. The sporangial wall of several cell layers; without an annulus. The sporangia dehiscing via median slits transverse to the axis bearing them (i.e., transversely to the pinnule axis).
Prothallus. Prothalli non-green, subterranean, mycorrhizal.
Distribution and habitat. In dry grassland, mostly upland. Throughout the Britain and Ireland, but commonest in northern and western Britain.
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, North Essex, 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, East Mayo, West Mayo, Sligo, Leitrim, Cavan, Louth, Monaghan, Fermanagh, East Donegal, West Donegal, Tyrone, Armagh, Down, Antrim, Londonderry.
Classification. Family Ophioglossaceae (C.T.W.); Ophioglossaceae (Swale and Hassler); Ophioglossaceae (Stace). Order Psilotales (Swale and Hassler).
Illustrations. • B. lunaria: Sowerby and Johnson (1859). • B. lunaria: Eng. Bot. 1835 (1886). • Botrychium and Ophioglossum: morphology of sporophyte and prothallus (Goebel). • Botrychium and Ophioglossum (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’.