British ferns (Filicopsida)
Sporophyte. The rhizomes short, stout; decumbent or shortly creeping; bearing scales (densely scaly, with broad, soft scales). Plants bearing markedly different fertile and sterile leaves (the fertile leaves longer and more erect).
Leaves aggregated terminally; to 30–100 cm long; dying in the autumn; compound; complexly divided; once pinnate, with conspicuously divided pinnae, or bipinnate with more or less undivided pinnules to bipinnate with conspicuously divided pinnules. Pinnae about 10–20 on each side of the leaf. The petioles shorter than the blades (with numerous uniformly pale brown, ovate scales at the base and fewer above); about 0.3–0.5 x the length of the blade (about 1/3–1/2 as long); vascularised by several discrete strands (derived via several leaf traces). Petiolar scales not golden brown (pale brown, sparse). Leaf blades in outline lanceolate, or oblanceolate. The longest pinnae the lowermost to near the base of the blade (the pinnae decreasing in length rather regularly acropetaly); 5–10 cm long. The pinnae not decreasing markedly in length basipetaly, the basal pinnae not or scarcely shorter than the longest pair. The venation of the lamina open.
The sporangia aggregated in sori. The sori sub-orbicular (rather large, forming a row down each side of the midrib of the pinnules, or more irregular on the larger pinnules); remaining discrete at maturity; with a true indusium. The indusia reniform and attached at the indentation; entire or sinuate, without glands. Paraphyses present in the sporangia. The mature spores monolete; without a perispore.
Distribution and habitat. Helophytic to mesophytic. In wet heaths, dune slacks, fens and marshes, often with Thelypteris palustris. Very local in SE and E England, Norkolk and Renfrews, formerly more widespread in England but seemingly decreasing there.
Vice-county records. Britain: North Somerset, East Kent, Surrey, Berkshire, East Suffolk, West Suffolk, East Norfolk, West Norfolk, Cambridgeshire, Huntingdonshire, Staffordshire, Nottinghamshire, Cheshire, South-east Yorkshire, North-east Yorkshire, South-west Yorkshire, Mid-west Yorkshire, North-west Yorkshire, Renfrewshire.
Classification. Family Polypodiaceae (C.T.W.); Dryopteridaceae (Swale and Hassler); Dryopteridaceae (Stace). Order Dryopteridales (Swale and Hassler).
D. x uliginosa (Braun ex Doll) Kuntze ex Druce = D. cristata x D. carthusiana.
Illustrations. • D. cristata: as Lastrea cristata, Eng. Bot. 1853 (1886). • D. cristata: Sowerby and Johnson (1859). • D. x uliginosa (D. cristata x D. carthusiana): as Lastrea uliginosa, Eng. Bot. 1854 (1886). • 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’.