About Dryopteris aemula (Aiton) Kuntze
Dryopteris aemula (Aiton) Kuntze produces a crown of fronds that grow from a short ascending rhizome. Its rachis is dark purple-brown, covered in red-brown lanceolate scales. The leaves are tri-pinnate, shaped triangular-ovate or triangular-lanceolate, and measure 15–60 cm (5.9–23.6 in) long. They are often arching, semi-evergreen, and pale yellow-green. Small, scattered sessile glands grow on the underside, or sometimes both surfaces, of the fronds. Slightly concave pinnae give the frond a characteristic crisped appearance. This plant has a hay-like scent. Sori, its spore-producing organs, grow in a single row along each side of the pinna midrib. The indusium covering each sorus is irregularly toothed, and its edge is lined with sessile glands. Dryopteris aemula cannot reproduce vegetatively, and relies entirely on spores to produce new individuals. This species is restricted to Atlantic coastal areas of western Europe and Macaronesia, with a highly oceanic distribution. It grows mostly in Köppen climate type Cfb, oceanic climates. Within Great Britain, it is confined to western districts, with only a small number of outlying eastern localities including The Weald. Its northern distribution limit is in Britain, and 20% of the world's total population of Dryopteris aemula is located in the United Kingdom.
