Myles would be great to chime in here, but I do know a few things that I can add.

- Tets are not necessarily sterile. There are quite a few hybrids with them. Some with other tets, and some with regular diploids, making them... (I think) Triploids, though it seems it is more common now to call the whole range Polyploids. I am sure someone will either confirm or correct this for me.

- I'm not so sure about self-pollinating, as that is something I never really do, but as far as crossing, one good example would be P. 'Betty Myles Young' which is P. 'Clear Sky' x P. loefgrenii Iporanga. You can see it and info on it on the new registrar list of hybrids from Les King. Here is the link to the PDF through Myles' site: http://www.passionflow.co.uk/downloads1.htm

- Lastly, I am pretty sure that P. x belotii is NOT a tet. I do know that it has been known to set empty fruit, and has no pollen. It is likely sterile due to the drastic genetic difference in the parents, P. alata and P. caerulea. This is fairly common in other hybrids as well, like P. 'Sapphire', P. 'Witchcraft', et cetera. That sure doesn't stop me from trying, though!

Hope that helps.

Eric

Thanks for the info Eric! As you can tell, I'm still learning. I don't know why I thought P. x belotii was a tetraploid. Myle's site has a really interesting description of its history. Thanks again, Myles, for your amazing site!

By the end of today I decided I am pretty sure my P. x belotii is starting to set a fruit. We'll see if it is empty! More likely than not, eh?

My belotii has never set a fruit, empty or not, even when surrounded by several other passies that could possibly pollinate it.

Thanks for the info Karyn! To be fair, I hand-pollinated with pollen from about 8 different species (from supersections pasiflora, decaloba, and tasconia no less!) just out of sheer obstination. That whole "don't tell me what I can't do" thing. And, as a reward, I'll likely get an empty fruit. Fun.

Anyone else know much about tetraploids? I'm still fascinated by the genetics of chromosomal crossover and re-assortment when the plants are 4n. Myles, you have actually accomplished this feat with your gorgeous Betty Myles Young?

Hi Shawn
What Eric says above is all correct. To give my own answers:-

1. Tetraploids are not, simply by virtue of being tetraploid, sterile, right?

Correct.

2. A tetraploid passiflora could theoretically self-pollinate or two could theoretically cross-pollinate, right?

The tetraploid P. 'Temptation' can self-pollinate but this is rare. Tetraploid's do cross-pollinate in practice e.g. Passiflora 'Monika Fischer' which is (P. incarnata x P. amethystina)4n x (P. kermesina x P. caerulea)4n.

3. Are there known passiflora tetraploids that self-pollinate or cross-pollinate?

See above.

4. I ask all this because I have one of the common P. x belotii and I'm wondering if it's possible for it or other tetraploids to set fruit, and, if so, if there is any chance the seeds would be viable. Anyone know?

I would confirm that P. x belotii is not a polyploid. There are a number of versions of this cross - some will not fruit at all as Karyn says and others will produce only empty fruit.

This is a very very complex subject and all I can say is that Passiflora are doing some unusual things which we are still struggling to understand. Together with Dr Les King I hope to publish a paper this year which will tell us more about the chromosome counts of these plants. Glad you like P. 'Betty Myles Young'.Though I say it myself it is an incredible vigorous free flowering hardy hybrid which is also very easy to root. P. 'Lambiekins' is another I am very proud of as is P. 'Poppet' soon to be released.

Here is a link that might be useful: Passiflora polyploids

Thanks Myles! Once again you have the answer to my questions!!! I can't wait to read the paper you and Dr. King are working on. I have reviewed the links on your site and others re:chromosome number, but there still seems to be a lot of uncharted territory. It's exciting that you might be able to chart some of it!

It make sense that hybrids would be more inclined to make unreduced eggs or pollen (based on the genetic mismatch of their parents) and might occasionally cross-pollinate with tetraploids.

This also seems to open the door to potentially finding pollinators for a lot of the cultivars previously thought to be "sterile."

If I may ask, are there tricks to making tetraploid hybrids? Is chemical intervention involved? I have heard in other genera of seeds being soaked in colchicine or human anti-metabolite drugs. (If theses are tricks of the trade meant to remain just that, I understand!)

shawn

Myles-

I'm also looking forward to reading that paper! Tetraploid hybrids are amazing in their color depth and richness.

I'm a big fan of the P. 'Poppet' picture posted on your website (for those of you who haven't seen it, check it out here http://www.passionflow.co.uk/passiflora-poppet.htm) and can't wait until it reaches US store shelves (online, that is! it's tough to find many "common" passies in Massachusetts, nevertheless rarer ones!).

Shawn-good luck with your tetraploid endeavors!

Cris

Hi Shawn to reply to
''If I may ask, are there tricks to making tetraploid hybrids? Is chemical intervention involved? I have heard in other genera of seeds being soaked in colchicine or human anti-metabolite drugs. (If theses are tricks of the trade meant to remain just that, I understand!)''
Shawn there is quite bit of info on my site but what exactly can be done in the laboratory and what in the garden and how I will keep close to my chest. What I will say however is that no one under any circumstances should try working with colchicine except under laboratory controlled conditons. It is as toxic as arsenic and some web sites are quite blasé about its use.
Myles

Here is a link that might be useful: Colchicine dangers

I agree with you Myles about the dangers of colchicine. My perspective is that of a physician. I prescribe colchicine to my patients with gout routinely. In addition to inhibiting microtubule formation in mitotic cells and causing polyploidy in plants, colchicine is a potent means of preventing uric acid crystal deposition in human joints, and thus for preventing gout flares.

As far as its use in plants, and polyploidy generally, I'm glad there are experts like you working on it! When and where might we anticipate your paper?

shawn

By way of update, my non-tetraploid P x belotii fruit grew to about an inch, dried out, withered, and fell off the vine. Oh well.