This section is from the book "Wayside And Woodland Blossoms", by Edward Step. Also available from Amazon: Wayside And Woodland Blossoms: A Guide To British Wild-Flowers.
Occasionally the rambler will find the Flax in cornfields and wastes, by oil-mills and in the neighbourhood of railway stations. Wherever it may be found it is an escape from cultivation. As a truly wild plant the "most used" flax is not known: in cultivation, as the parent of linen garments, it has been known from the infancy of the human race. To-day the exports of flax and linen from the United Kingdom are worth about £5,500,000 per annum. It is therefore a plant that would be entitled to respectful consideration when we meet it, even if it had no grace or beauty to commend it to us.
Common Flax is an annual plant, with erect slender stems about a foot and a half high. Its narrow lance-shaped leaves are arranged alternately and at a distance from each other. The flowers are large, and purplish-blue in colour. Five is the number dominating the structure of the flower: sepals, petals, stamens, glands, ovary (5 cells), styles - all in fives. It flowers in June and July.
There are three other species that are truly wild in Britain:
I. Purging Flax (L. catharticum). A smaller species, half a foot high, with white flowers, affecting heaths and pastures. It has opposite, very narrow leaves, and the unopened buds nod. Flowers June to September.
II. Perennial Flax (L. perenne). A very rare perennial plant with exceedingly narrow leaves, alternate on the numerous wiry stems. Plant about 2 feet high. The large bright-blue flowers, which may be found from June to September, are of two forms, long-styled and short-styled, like the Primroses (see p. 2), and for a similar purpose. On chalky soils from Durham to Essex.
III. Narrow-leaved Flax (L. angustifolium). Leaves alternate, as narrow as in the last species, but smaller and not so plentiful. Flowers smaller and paler, petals smaller in proportion to the calyx. Flowers May to September. Sandy and chalky pastures, not farther north than Lancashire.