Linum perenne subsp. perenne

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1981, Flora Europaea. Volume 2. Rosaceae to Umbelliferae, Cambridge University Press : 209

(a) Subsp. perenne :

Stems (20-)30-60 cm, erect from an ascending base. Middle cauline leaves 1-2*5 mm wide, 1-veined or obscurely 3-veined. Inner sepals 4*5-5*5 mm, very obtuse, exceeding the outer sepals by 0*5-1 mm. Capsules 5-7 mm. Pollen grains with furrows. 2n= 18. C. & E. Europe.