Symphytum tuberosum subsp. tuberosum

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1972, Flora Europaea. Volume 3. Diapensiacea to Myoporaceae, Cambridge: Cambridge University Press : 104

(a) Subsp. tuberosum :

Rhizome stout, up to 12 mm in diameter, the tuberous portions of irregular shape and close together. Cauline leaves usually 6-12. Inflorescence with 8-16(-40) flowers. Corolla-scales 5-5-7-5 mm, not more than 2 mm wide. Stamens with filament as long as anther. Nutlets up to 4 mm. 2n = 144. • W. Europe.