I grew the Passiflora Cerulea from seed many years ago and planted it in the ground next to my former home (a tall stone townhouse). It would come back vigorously every year, climbing a raised basement and two stories and then sprawl all over the roof deck. While the foliage was thick and healthy and its stems were as thick as those of a grape vine, it produced very few blossoms. Here in my new home, I grow it in a large pot next to an arbor and this year in addition to many dozens of flowers it made three fruits but after they turned yellow and fell to the ground I found them to be hollow and when opened they looked like an orange peel with white fiber, but no juice or seeds. So I have just had to be happy with my sucess in getting the fancier varieties to bloom. My favorite this year has definitely been "Monika Fisher " for it's abundance of larger beautifully colored blooms. In my opinion "Monika" has beatened both "Marian" (a new, seed grown/selected variety I got last year from a hybridizer on ebay), and even the very frilly "Incense" with its amazing fragrance.
"Incense" with "Monika":
"Monika" with "Marian"
Actually I am very happy to have had so many beautiful passion vine flowers this year in tropical Pittsburgh PA! lol Now if that 5' South American Red passion vine would just flower before frost in the next five or six weeks, all my passion plants varieites will have produced blossoms this year!