British ferns (Filicopsida)
Aspidium lonchitis (L.) Roth.
Sporophyte. The rhizomes stout; ascending; bearing scales. Plants with no clear distinction into fertile and sterile leaves.
Leaves aggregated terminally; to tough, 20–60 cm long; persistent; circinnate; compound; simply divided (simply pinnate, the pinnae asymmetrically and narrowly triangular- to oblong-ovate, with with no free pinnule at the base, only a deltoid lobe, serrate, with straight spine-pointed teeth, the teeth often serrulate or crenate). Pinnae 20–40 on each side of the leaf. The petioles shorter than the blades (only a sixth as long or less, clothed with more or less ovate, reddish-brown scales); vascularised by several discrete strands (derived via several leaf traces). Leaf blades in outline linear lanceolate, or linear; leathery. The longest pinnae around the middle of the blade (the pinnae decreasing in size downwards, the lowest 5 mm long or less); 1–3 cm long. The venation of the lamina open.
The sporangia superficial; aggregated in sori. The sori sub-orbicular (about 0.5–1 mm in diameter, usually confined to the basal parts of the leaves, in a row down each side of the midrib of the pinna, nearer the midrib than the margin, and a double row down its basal lobe, with the vein upon which the sorus is borne not or only shortly continued beyond it); remaining discrete at maturity; with a true indusium. The indusia peltate; irregularly toothed. Paraphyses absent. The mature spores monolete; with a perispore.
Distribution and habitat. On base-rich substrates. Basic rock crevices, scree and ravines, mostly above 600 m, but somtimes much lower. Local in northern England, central and northern Scotland, Caerns and Dumfries, and in western Ireland, naturalized in Northants.
Vice-county records. Britain: South Wiltshire, Northamptonshire, Caernarvonshire, North Lincolnshire, South-west Yorkshire, Mid-west Yorkshire, North-west Yorkshire, Durham, North Northumberland, Westmorland, Cumberland, Isle of Man, Dumfriesshire, Berwickshire, Stirlingshire, West Perthshire, Mid Perthshire, East Perthshire, Angus, South Aberdeenshire, Banffshire, Moray, East Inverness-shire, West Inverness-shire, Argyll Main, Dunbartonshire, Mid Ebudes, North Ebudes, West Ross, East Ross, East Sutherland, West Sutherland, Caithness, Orkney islands. Ireland: South Kerry, North Kerry, West Galway, West Mayo, Sligo, Leitrim, Fermanagh, East Donegal, West Donegal.
Classification. Family Polypodiaceae (C.T.W.); Dryopteridaceae (Swale and Hassler); Dryopteridaceae (Stace). Order Dryopteridales (Swale and Hassler).
P. x lonchitiforme (Halacsy) Bech. = P. setiferum x P. lonchitis, and P. x illyricum (Borbás) Hahne = P. aculeatum x P. lonchitis are sterile and intermediate in form.
Illustrations. • P. lonchitis: Eng. Bot. 1859 (1886). • P. lonchitis: Sowerby and Johnson (1859). • 9 British Dryopteridaceae (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’.