Convolvulus tricolor subsp. tricolor

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 : 81

(a) Subsp. tricolor :

Distal part of sepals broadly ovate-oblong, obtuse, subacute or shortly acuminate, shorter than to about as long as proximal part. Throughout the range o f the species, but perhaps not native in Sicilia.