British ferns (Filicopsida)
Common Adders Tongue.
Excluding O. azoricum C. Presl = O. vulgatum subsp. ambiguum (Coss. & Germ.) E.F. Warburg.
Sporophyte. The rhizomes subterranean, very short, erect (with new plants arising from adventitious buds on the roots); 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 a fertile, non-laminate spike - see below), or bearing markedly different fertile and sterile leaves (the fertile leaf sometimes accompanied by one or two sterile blades). Plants having sterile blades mostly 4–15 cm long, the sporangia 10–40 on either side of the spike.
Leaves to (4–)8–20(–45) cm long; dying in the autumn; not circinnate; compound (when fertile, see above, though the green blade is simple), or simple and compound (when sterile blades occur). 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 (3–)4–15(–30) cm long (ovate to ovate-lanceolate or oblong, basally rounded to cuneate); simple and entire; green blades with free vein endings within the network. The fertile spikes 1.5–5(–7) cm long; unbranched. The petioles vascularised via a single strand (this representing a single leaf trace arising from the lower angle of the leaf gap). The venation of the lamina reticulate (i.e., in the sterile blade, although it exhibits minute free vein endings inside the network).
Eusporangiate. The sporangia all alike, relatively massive, sessile and coalescing in two rows on the spikelike fertile component of the leaf (10–40 on either side of the spike); 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 axis of the spike). The mature spores trilete.
Prothallus. Prothalli non-green, subterranean, mycorrhizal.
Distribution and habitat. On base-rich substrates, on neutral substrates, and on acid substrates. In grassland, dune-slacks, ditches and open woods, mostly lowland. Frequent throughout most of 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, 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, 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. • O. vulgatum: Eng. Bot. 1835 (1886). • O. vulgatum: Sowerby and Johnson (1859). • O. vulgatum: morphological details of sporophyte (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’.