Passiflora caerulea?

Hi, I'm a bit new at this, but I have a couple of passion vines in my back yard and have a few questions. From the other threads I've read, I know that someone in this crowd will undoubtedly know the answers! First, I've attached a photo from last year. Am I correct in saying this is likely a Passiflora caerulea? If so, are there sub branches of this? I've seen other names like 'Blue Crown' and 'Blue Horizon' with similar looking flowers. Are these other names just cultivar names for Passiflora caerulea, or are they hybrids of some type? I'd be interested in hearing if mine is 'regular' or 'different'.

Next, do these plants spread from seeds or runners (or both)? Most of the passion flower sites I read said seeds only, but I've got them coming up everywhere and I have a hard time believing they aren't also coming up from the roots. Also, I'm assuming the seeds are in the fruits? My plants have green fruits that turn yellow and pretty much dry on the vine. If I open them, there are no visible seeds. Some photos I've seen show passion fruits with large seeds, so does that mean mine is sterile (again pointing to the runner theory)? Or are the seeds just too small to see?

This is my first post, and I'd like to thank the Dave's Garden regulars for the great Passion Flower information in other threads. I feel I've learned a lot already.

And here's a photo from today. There are hundreds of flowers and buds and I've got to keep cutting it back as it is already choking out a wisteria (and generally trying to get into everything else around it). Also, there are numerous Gulf Fritillary (Agraulis vanillae) butterflies around along with their caterpillars, but there is so much vine to eat, they haven't dented it yet.

stephen...I am glad you are asking the questions that you are...I also have a passionflora that looks like yours. I believe the caerulea is the type of passionflora that it is. Mine has the fruit too, but turns orange and you can see the seeds. Like yours, mine has come up all over my yard, including under a brick patio...I believe it from runners also, not seeds.

It will be good to see what someone who knows answers...

Margie

Stephen, It does look like you have a P. caerula, which is a species of Passiflora. 'Blue Horizon' and 'Blue Crown' are hybrids created by crossing similar species of Passiflora, then propagating through cuttings. Seeds of the hybrids won't come true, and will revert back to one of the original parents (as in the case of hostas), or will be sterile (as in the case of a lab plant, like some types of Calibrachoa). In your situation, the passion flower is probably propagating through above-ground runners. Cuttings from the plant will root readily, and if a part of the plant touches the ground, it will often root and branch off from the original plant. It is this characteristic that causes people in certain regions to consider it a beautiful weed. If you don't want it to overwhelm the wisteria, you'll just have to aggressively rip the unwanted rootings out of the ground, as it can be a bit of a thug when it gets out of the place that you want it.

I'm not sure why you aren't seeing seeds. They are present in the fruit, and they will spread from seed readily, especially in warmer regions. I think if you were to leave the fruit on the vine to dry on its own for even longer, the surrounding fleshy tissue would completely dessicate, and the seeds would become obvious. In your case, the plant would come true from seed, as it does seem to be a regular P. caerula, a true species, and it is most likely not sterile unless there is something wrong with the plant. Even if your plant were a hybrid that looks very similar to P. caerula, it would produce seed, just seed that either wouldn't be viable, or would not germinate true to the parent. In this case, passion flower isn't much different from other plants that hybridize readily.

-Greg