British ferns (Filicopsida)


L. Watson and M. J. Dallwitz

Asplenium adiantum-nigrum L.

“Black Spleenwort”.

Excluding A. onopteris (L.) Heufl.

Sporophyte. The rhizomes short; creeping (or decumbent); when young, bearing scales (the scales brown, subulate). Plants with no clear distinction into fertile and sterile leaves.

Leaves aggregated terminally; to 10–50 cm long; persistent; compound; complexly divided; bipinnate with more or less undivided pinnules to tripinnate with undivided ultimate pinnules (the pinnae varying from lobed to pinnate). Pinnae acute to very shortly acuminate, 6–15 on each side of the leaf. The petioles about as long as the blades (blackish, scaly at the extreme base); vascularised via a single strand (representing fusion of a pair of leaf traces). Leaf blades in outline acute to very shortly acuminate, ovate-triangular, or lanceolate-triangular; somewhat leathery to ‘herbaceous’. The longest pinnae the lowermost; 2–6 cm long (decreasing markedly in length upwards). The venation of the lamina open.

The sporangia superficial; initially aggregated in sori. The sori linear elongated (1–2 mm long, two to several per segment, borne obliquely, occupying the greater part of the length of the lateral veins but nearer the indistinct segment midrib than its margin); becoming confluent when mature (finally occupying the greater part of the segment); with a true indusium. The indusia attached on one side along a vein; whitish, entire or sinuate. Paraphyses absent. The mature spores monolete; with a perispore.

Distribution and habitat. On base-rich substrates, on neutral substrates, and on acid substrates. In rocky places,in woods, banks and open sites, often on walls. Common 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, 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.); Aspleniaceae (Swale and Hassler); Aspleniaceae (Stace). Order Aspleniales (Swale and Hassler).

X Asplenophyllitis jacksonii (Alston) Lawralrée is a sterile hybrid of this species with Phyllitis scolopendrium; Adiantum x ticinense D.E. Mey. = A. adiantum-nigrum s. lat. x subsp. A. onopteris; A. x sarniense Sleep = A. adiantum-nigrum x A. obovatum; A. x contrei Callé, Lovis & Reichst. = A. adiantum-nigrum x A. septentrionale.

Illustrations. • A. adiantum-nigrum: Eng. Bot. 1874 (1886). • A. adiantum-nigrum: Sowerby and Johnson (1859). • A. adiantum-nigrum var. acutum: Eng. Bot. 1875 (1886). • A. adiantum-nigrum: details. • 9 British Aspleniaceae (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.’.