Hi Christine,

If I were you I would contact Elizabeth Peters at Grassy Knoll Exotics. She sells over a hundred varieties and I assume she'll know the ins and outs of what can pollinate what, and if you like she can even sell you the plant(s)she recommends. She's incredibly nice and helpful and she sells great stuff. Even if you don't plan on buying I would assume she'd be happy to answer your questions. She might not get back to you immediately by email.

elizabeth@gkexoticplants.com
360.241.6954
http://gkexoticplants.com/

Here's a list of some with edible fruits:

http://www.hort.purdue.edu/newcrop/nexus/passiflora_spp_nex.html

I think P. caerulea is supposed to be hardy to zone 7--you should check. The fruit is edible; I think you'd find differences of opinion as to whether it's worth eating. Frequently you see it described as good for jam, if that's any indication.

Of course there's no reason you can't grow more tender species/hybrids inside when it's cold, and outside when it's warmer.

As far a P. incarnata goes, I've never grown the plant, however I posted an abstract from a paper in a couple recent threads (at the moment they are just a few down)that says that it's self-incompatible. I don't know personally if that's accurate, but nobody has posted to suggest otherwise.

One way to find out if something will pollinate another is to see whether a hybrid exists between the two species. There are lists of hybrids--see Myles Irvine's site:

http://www.passionflow.co.uk/downloads1.htm

This would take a bit of work. The problem with checking hybrids is that you only have to get 1 viable seed out of one fruit of who knows how many attempts to make a hybrid. You want to get fruits full of seeds (+ the edible associated arils) all the time, and not all pollen will give you that. That's where someone like Elizabeth comes in handy. Perhaps someone who has grown P. incarnata can also reply to your post? I know that hybrids with P. caerulea and P.edulis exist, but I don't know how reliably you get good fruit using these as pollinators.

I can give you a seedling of P.edulis, however I don't think it would bloom until at least next year. I can also take cuttings off P.edulis 'Frederick' and/or 'Nancy Garrison', but not until later in the year as they are covered with buds. I suspect that these would bloom for you the following year--a cutting I took in November or December already does have buds.

All the leaves, stems and immature fruit produce natural cyanide as a defense against being eaten. I know incarnata leaves can be processed in such a way as to make a tea (are the cyanides volitile? Can mere drying of the leaves neutralize them?) but I've never been interested enough to look into it. I do know that when I'm trimming back rampant growth, I can smell the sharp cyanidic odor coming from the damaged greenery.

Many passiflora species produce edible fruit. Not all is palatable, however. This can vary even among members of the same species. My Constance Eliot produces semi-sweet fruit that is OK, whereas my regular caerulea produces unpleasantly bland fruit that's unpleasant to taste, much less eat. Foetidas generally produce sweet, but small fruit. Decalobas produce small, inedible fruit that is occasionally toxic. The various passiflora encyclopedias available on Amazon are good reference sources for which fruit are edible and which aren't, as is Myles' Passionflow site.

I was curious about cyanide and P. incarnata, so I looked it up.

On Google books there is a book called The American Pharmaceutical Association Practical Guide to Natural Medicines by Andrea Peirce. They have an entry on Passiflora incarnata, which they simply refer to as "Passionflower". An excerpt:

"Unlike other Passiflora species, Passiflora incarnata does not produce the edible, succulent fruit referred to as passion fruit. Passionflower does not contain the poison cyanide, as some sources incorrectly suggest; they may have mistaken Pasiflora incarnata for Passiflora caerulea, the ornamental blue passionflower that does contain this toxin."

So is this correct? The part about it not getting fruit strikes me as rather odd.

Wow - Seems I am in way over my head here. I am primarily interested in the plant as a medicinal herb. "Passionflower is used internally to treat nervous restlessness, sleep disorders, anxiety, neuralgia, irritability and overcoming the difficulty in falling asleep." They are speaking of Passiflora Incarnata here. It is said to have narcotic properties. I will contact Ms. Peters for more information from her, and maybe a Q about safe use on the Herbalism forum. I very much appreciate all of your help!!