Cotton-grass, or bog cotton (Eriophorum aungustifolium), is a hardy, herbaceous, perennial member of the sedge family and so not technically a grass at all. It thrives in the harshest of environments, where it can take advantage of the lack of competition, including peaty, acidic soils, open wetlands, heaths or moorlands. It begins to flower in April or May and, after fertilisation in early summer, the small, unremarkable brown and green flowers develop distinctive white bristle-like seed-heads that resemble tufts of cotton. In abundance, E. angustifolium can grow with enough density to disguise wetland and bog. Consequently, it may be used as a natural indicator of areas which are hazardous and to avoid travelling through.
In Scotland, cotton grass fibres have been used in the manufacture of cloth. Early records show the use of the plant as a filling for pillows and mattresses instead of goose down (as observed by Dr John Lightfoot during his travels through Scotland in 18th century- he travelled along with Pennant who wrote his well known 'Tour of Scotland', while Dr Lightfoot published his work 'Flora Scotica').
Clothing made from cotton-grass fibres is also mentioned in Scottish folk tales. In one, described by William Milliken and Sam Bridgewater, a girl refuses a suitor unless he procures a gown of canach (cotton grass). In another, after a bewitched prince becomes a 'creature neither man nor beast' , his father asks local girls to weave three shirts from canach down. Only one suceeds in doing this. When the prince receives the shirts he reverts to his 'handsome old self' and, inevitably marries the girl.
It is not clear whether the plant's role in these stories reflects a genuine belief in the powers of a caineachan shirt, or whether it is simply a convenient way of symbolising a precious object or an act of unusual patience and determination.
In Scotland, during First World War, cotton grass was used to dress wounds.
Resources:
'Vickery's Folk Flora' - R. Vickery, 2019
'Flora Celtica, Plants and People in Scotland' - W.Milliken & S.Bridgewater, 2013
'The Gaelic names of plants' - J.Cameron, first published 1900, 2019 re-print