About Cryptogramma crispa (L.) R.Br.
Cryptogramma crispa fronds reach 30 centimetres (12 inches) in length and occur in two distinct forms. Sterile leaves are 2–3-pinnate, with pinnules measuring 5–10 mm (0.2–0.4 in) long by 3–7 mm (0.1–0.3 in) wide. Fertile leaves are 3–4-pinnate with narrower pinnules. Their sori are scattered along veins, each enclosed by a strongly enrolled false indusium. The sporangia are yellow and mature around midsummer.
This species grows among acidic rocks in locations where snow persists until late in the year. It acts as a pioneer species on stable scree slopes, and can also be found on cliffs and dry stone walls. In Europe, Cryptogramma crispa has an Arctic–alpine distribution: it grows in the mountains of Central and Southern Europe, as well as in northern parts of the continent including Scandinavia and higher ground of the British Isles. In Ireland, it is rare and concentrated in the east of the country; this distribution led Praeger to conjecture that Irish individuals are recent colonists from Great Britain, arriving as airborne spores. On the Isle of Man, it is a rare amber-listed plant of moderate conservation concern, and is a protected species listed on Schedule 7 of the Wildlife Act 1990.
Similar plants that may belong to the same species grow in East Asia and North America, though these populations are usually classified as a separate taxon. Spores identifiable as Cryptogramma crispa have been found in last glacial period deposits in Snowdonia, as well as in lower-lying sites in Cheshire.
