The only one I know of that is available commercially is P. 'Byron Beauty', which is a complex tetraploid hybrid between P. incarnata, P. edulis edulis, and P. edulis flavicarpa. They cross pretty easily, although most of the hybrids are sterile.
'Byron Beauty' is quite fertile, but is self-incompatible, and will need another compatible tetraploid for cross-pollination if you want fruit with seeds. It will often set fruit from diploid pollen, but the fruits will typically be hollow.
You can try bud-pollination, where you pry open a bud the day before it opens, and apply fresh pollen from another opened 'Byron Beauty' flower. This will sometimes by-pass the self-incompatibility and produce fruit with seeds.
My 'Byron Beauty' has several fruits on it now, using P. 'Byte' pollen. P. 'Byte' is 'Byron Beauty' x 'Temptation', and has been root hardy here the past two winters. The 'Byron Beauty' fruits are supposed to have a very good flavor.
I wanted to share this info. My 'Inspiration" has bloomed all summer and made alot of fruit. Today I noticed one that had started shriveling and gave it a try. It was great if you like very sweet tart type candy. It was just like the fruit from the maypop but so very sweet tart. I loved it.
I will try next summer to get me a cross between the Byron Beauty I have and the Inspiration.
Also, what is the trick to sprouting passiflora seeds?
I will try the orange juice soak. I tried years ago to sprout a passiflora and they never came up. Before I try to sprout these Inspiration seeds I am wondering if there is a trick to it. Like having to really clean and dry citrus seeds before planting them. Or a cool spell to break dormancy ?
Sprouting seeds depends on the species, but generally, you want to soak the seeds in water for 2-3 days, with 2-3 changes of water, then place in a warm location in moist soil. I have found that the seeds from the Maypops here need a cold stratification. Two months in the refrigerator (in moist soil), then moving to warmth (heating pad 80-90F), usually gives fast germination. I'm not sure if the incarnata hybrid seeds need it, but it probably would not hurt. The tropical species (most species) will not need any cold treatment. You could soak in orange juice, but water probably works just as well.
Thanks for the tips... I know that 'Inspiration' is a variation of 'Incense'
which I think is a incarnata-cincinniti (sp) cross. Anyone know what else they added to make it 'Inspiration'? I don't know why I am bothering to try and sprout the seeds as I have luck with cuttings using
rootone and a cloche. Maybe I just want to see if any will revert to something else.