British ferns (Filicopsida)
A. lanceolatum Huds., p.p.; British specimens being referable to subsp. lanceolatum (Fiori) P. Silva.
Sporophyte. The rhizomes creeping to erect (or decumbent); bearing scales (narrow, subulate, dark brown scales).
Leaves aggregated terminally; to 10–30 cm long; persistent; compound; complexly divided; bipinnate with more or less undivided pinnules to bipinnate with conspicuously divided pinnules (bipinnate at least at the base, the pinnae subsessile, dentate, the pinnules cuneate at the base, and the lowest one on the upper side of the pinna sometimes larger than the others and somewhat lobed). Pinnae 8–20 on each side of the leaf (up to 20). The petioles shorter than the blades to about as long as the blades (from about half as long to almost as long, blackish, scaly at the extreme base); vascularised via a single strand (representing fusion of a pair of leaf traces). Leaf blades in outline oblong, or elliptic, or lanceolate (oblong-lanceolate to lanceolate-elliptic); leathery to herbaceous. The longest pinnae about a third of the distance from the base of the blade to around the middle of the blade (but the basipetal decrease in length very gradual); 1–5 cm long. The venation of the lamina open.
The sporangia superficial; protected; at least initially aggregated in sori. The sori linear elongated (1–2 mm long, borne obliquely, several per side along the veins of the pinnule, nearer its margin than its midrib); becoming confluent when mature (sometimes), or remaining discrete at maturity; with a true indusium. The indusia attached on one side along a vein; whitish, entire. The mature spores monolete; with a perispore.
Distribution and habitat. On rocks, walls and hedgebanks, especially near the sea. Common in central Ireland, SW England and Channel Islands, frequent in W Wales, scattered in Ireland and western Britain north to W Sutherland.
Vice-county records. Britain: West Cornwall, East Cornwall, South Devon, North Devon, South Somerset, East Sussex, West Kent, West Gloucestershire, Glamorgan, Carmarthenshire, Pembrokeshire, Cardiganshire, Montgomeryshire, Merionethshire, Caernarvonshire, Anglesey, South Lancashire, North-east Yorkshire, South-west Yorkshire, Cumberland, Kintyre, West Sutherland, Channel Islands. Ireland: South Kerry, North Kerry, West Cork, Mid Cork, Wexford, Carlow, Wicklow.
Classification. Family Polypodiaceae (C.T.W.); Aspleniaceae (Swale and Hassler). Order Aspleniales (Swale and Hassler).
X Asplenophyllitis microdon (Moore) Alston is a sterile hybrid of this species with Phyllitis scolopendrium.
Illustrations. • A. obovatum: as A. lanceolatum, Eng. Bot. 1873 (1886). • A. obovatum: Sowerby and Johnson (1859). • Asplenium obovatum and A. fontanum (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’.