From the Passiflora "Bible", "Passiflora: Passionflowers of the World", Ulmer and MacDougal. p. 13:

"Blossom size spans from less than 1 cm in Paassiflora suberosa to 17-18 cm in some clones of P. insignis or P. vitifolia. A diameter of even 22 cm, found in a collection of P. speciosa in Brazil, is reported by Reto Gamma"

I would add that P. 'Mission Dolores' (P. parritae x P.antioquiensis), can also be 7 inches (18 cm).

Here is a link that might be useful:

This post was edited by mark4321 on Fri, May 9, 14 at 21:31