Athyrium flexile, commonly known as Newman's Lady-fern, is a fern

Fern

A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...

 endemic to Scotland.

It is an upland variety typically found above 750 metres on screes made up of siliceous rocks such as quartzite

Quartzite

Quartzite is a hard metamorphic rock which was originally sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to gray, though quartzites often occur in various shades of pink...

 and granite

Granite

Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...

 in the Highlands

Scottish Highlands

The Highlands is an historic region of Scotland. The area is sometimes referred to as the "Scottish Highlands". It was culturally distinguishable from the Lowlands from the later Middle Ages into the modern period, when Lowland Scots replaced Scottish Gaelic throughout most of the Lowlands...

 where it is found at only four sites. It is a snow-tolerant species, the snow lie

Snow patches in Scotland

Long-lying snow patches in Scotland have been noted from at least the 18th century, with snow patches on Ben Nevis being observed well into summer and autumn...

 protecting it from frosts.

Athyrium flexile is a stunted variety of Alpine Lady-fern A. distentifolium

Athyrium distentifolium

Athyrium distentifolium commonly known as Alpine Lady-fern is a fern found in widely in the Northern Hemisphere.It is a common upland variety above 600 metres in the Highlands of Scotland, with more than 10% of the UK population being found in the Cairngorm mountains, especially on scree...

, a single gene mutation accounting for the difference between the two. It is considered by some experts to be a variant of Alpine Lady-fern (Athyrium distentifolium var flexile) rather than a distinct species.

Regarded as nationally scarce and vulnerable

Vulnerable species

On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...

, more than 75% of the population is found in the high Cairngorm mountains

Cairngorms

The Cairngorms are a mountain range in the eastern Highlands of Scotland closely associated with the mountain of the same name - Cairn Gorm.-Name:...

 including the boulder field plateau of Braeriach

Braeriach

Braeriach is the third highest mountain in Great Britain, surpassed only by Ben Nevis and Ben Macdui. It is the highest point in the western massif of the Cairngorms, separated from the central section by the pass of the Lairig Ghru. The summit has a crescent shape, with several corries...

 and in upper Glen Doll

Glen Doll

Glen Doll, also sometimes spelt Glendoll, lies within the Cairngorms National Park, Scotland, at the top of Glen Clova, in an area of steep hills, Corries and Munros. It includes the Corrie Fee Nature Reserve, which has many endangered plants....

. It is found as high as 900 metres in Glen Einich.