I know that Passiflora species are often self-incompatible, so when I decided to grow P. maliformis in my greenhouse last year, I planted two distinct seedling specimens. Unfortunately, one of them was planted too close to the exterior wall, which it grew up and got too cold, so it looks to have died over the winter.
I’m expecting that the healthy one (~30 ft of vine sprawling across the greenhouse rafters) will flower this year, but it doesn’t seem like anyone sells this species as larger plants rather than seeds, so I’d like to pair it with some other Passiflora species, if there are any that are compatible.
Any ideas or resources that anyone has to share would be much appreciated!
I don’t own P. maliformis. So no specific experience with this species (i have loads of others though)
A lot of passiflora readily hybridize. easiest within subgenus (tacsonia’s are hard to cross with non tacsonia)
If you look at many of the wonderful hybrids of passiflora you see however that a really large group of different species have been crossed.
From experience i can however note that some crosses are possible. But tend to yield little seeds in the fruits. Usually enough to grow out for a hybrid. But not always sufficient for good fruit production for eating.
I’d probably look at a phylogenetic analysis/tree. (i do this to guess which passiflora might be worth crossing, for ornamental hybrids)
This shows how closely related species are based on DNA
see the following link for more explanation. (i have little expertise on phylogenetics, so apologies if i read the analysis wrong)
https://www.pnas.org/content/93/23/13429 (little bit older, so not sure it’s up to date. But might be of intrest if your curious of the math behind the analysis)
but
P. Incarnata (maypop) (edible, decent)
P. Caerulea (edible, often not good tasting (sweet but “dusty”))
P. Edulis (edible tasty, most of the grocery passionfruit)
will likely also work
Good point that pollination may be low and hence pulp quantity limited.
I also know a guy who grew incarnata for fruit and used caerulea as his pollinator. He never mentioned hollow fruits but ….
Thank you for all this information, and especially the phylogenetic tree! From a couple quick searches the closest relatives don’t seem to be commercially available (logee’s has one out of stock though), but it looks like incarnata and edulis are both worth trying at least.
I do also have a third (stunted) seedling in a pot, which wilted badly and mostly defoliated, but appears to be alive at least, so I may try grafting that on the big healthy one as another option. Here’s that one:
Nottttt really. Most of his work is on flower color and size and vigor. However with all the various seedlings and crossing that’s happened in my garden, it’s possible some of the edulis or tucumanensis genes have contributed to good flavor. I have had some excellent ones.
i can’t find the original research paper. But i think the goal was to produce a hybrid that could produce quality fruits in colder climate zones. Keep in mind it’s a tetraploid though. So you want another tetraploid nearby for pollination.
I’ve been growing two different batches of complex hybrid Passiflora for a couple years now. As of last year I was able to get many flowers produced throughout both hybrid batches which I hand pollinated in any and every direction possible (not knowing which ones would accept pollen from which sources). Unfortunately, one of the hybrid groups set a total of zero fruit despite repeated attempts at hand pollination. The other hybrid group set fruit on about half the plants while the other half failed to set.
This is just something to keep in mind. Just because you can successfully cross various species does not mean the resulting progeny will be able to bear fruit. I think part of the problem is that there are a lot of variations of ploidy within Passiflora and the person who produced the two seed batches from which I did the grow out was intermixing ploidies indescriminately thinking that it wouldn’t matter. I suspect that if you make carefully planned crosses which account for ploidy you will have a better chance of maintaining fertility through multiple generations of hybrid offspring. For example diploid x diploid = most likely outcome - diploid (very likely fertile), diploid x tetraploid = most likely outcome - triploid (probable fertility issues), diploid x hexaploid = most likely outcome - tetraploid (very likely fertile), etc.
I’m not aware of any hexaploid Passiflora either, but it would be possible if a triploid were chromosome doubled to restore/improve fertility. Just something to keep in mind with breeding decisions.
Edit: A search on Google Scholar indicates that there are some hexaploids found within the genus Passiflora, but none were names I recognized. I suspect they aren’t commonly available, but as stated above it is foreseeable that new hexaploids could arise.
Any interest in swapping or selling woody cuttings from any that have fruit you liked? P. maliformis supposedly has tasty fruit, just small and difficult to open. It clearly is not at all cold hardy, though, if that’s what killed this one, since the coldest it got in the greenhouse this winter was the low 40s. But most nights it’s in the upper 40s in there, which I guess is too cold. Though the one away from the wall looks ok.
The types I have should in theory propagate well from root cuttings since they all trace back in part to P. incarnata. That said, I am planning to evaluate one more year before propagating any. I already composted a number which were low vigor or produced tiny fruit, but I have two with smallish (but maybe just big enough to be worthwhile) fruit and one with pretty good sized fruit as well as a hand full I wanted to give one more chance at attempting to get to set fruit before composting. I also am growing out a handful of straight P. incarnata seedlings to evaluate, but haven’t yet fruited most of them.
I know it’s not the timeline you’re hoping for, but check back with me in the fall.
I would not be able to try growing anything that isn’t at least almost hardy here though since I do not heat my greenhouse and it sometimes drops below freezing.
There would be no suitable material for grafting anyways. They are all out in the cold and have died back for winter. Last winter I kept the hybrids in my unheated greenhouse, but they’re all getting hardiness tested this winter. So far they’re all still alive and despite dying back they on average have retained a longer section of green at the base of each stem than the pure P. incarnata seedlings I have to compare them with. They actually withstood a good bit of cold before dying back too.
Late December was pretty cold! Any that made it through this winter have a shot at most PNW winters.
Here’s the base of my bigger first year seedling of maliformis, which turned fall colors on about 75% of the leaves and dropped them, but no signs of any dead stems and not holding any dead leaves, still mostly green on the tender leaves near the growing tips:
I had originally bought those seeds because it was described as growing in “somewhat cooler than tropical” climates at higher elevations, so I was hoping it was a bit hardier, but I can’t imagine this thing surviving a frost.
The yellow pitaya seedling in the pot next to it in that photo may be joining it in the ground soon. I’m not sure if dragonfruit will grow up a Passiflora, but figure it’s worth a shot, and I can support them with twine from above, too.
