Asperula lutea subsp. rigidula

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1976, Flora Europaea. Volume 4. Plantaginaceae to Compositae (and Rubiaceae), Cambridge University Press : 8

(b) Subsp. rigidula (Halácsy) Ehrend. , Bot. Jahrb. 80: 402 (1961):

Stems 18- cm, robust, with short, stiff hairs 0.1-0.2 mm, particularly towards base. Leaves robust, rigidly patent, more or less shortly hairy to glabrous, with awn c. 0.5 mm; midrib comprising more than 3/4 of width of leaf; margin distinctly revolute. Inflorescence more or less branched. Corolla 3.5-5.5 mm, usually yellowish, glabrous or hairy. Fruit 1.5-2.5 mm, papillose, glabrous (rarely hairy)) Mediterranean zone, calcareous and siliceous soils. S.E. Greece, Evvoia .