another clematis for ID

[Carolyn]

I grew this clematis from seed 3 or 4 years ago and now it is flowering for the first time. The label has, of course, disappeared and now I am left wondering what this is. I thought it was Clematis grata, collected by Chris Chadwell in the Himalayas, but having searched for photos, I now have doubts. This flower reminds me of montana, both in shape and size. I haven't sown any montana seeds.
Any suggestions as to ID? And has anyone else grown and flowered the CC Clematis grata?

[Growild]

Hi Carolyn, I have a Clematis grata from the same CC collection - though it hasn't flowered yet. If it does flower this year I'll post pic's ... but yours as you were thinking isn't that species. I remember from the same year CC did send out a collection of C. montana.

[Carolyn]

Lisa,
I didn't ever get montana seeds from Chris, so if it is a montana, then it's been a mix-up in seed packets. It's strange that it is flowering just now - I know that montana will occasionally produce a flower or two out of season, but this seems to be the main flowering for this plant. I will wait and see what it does next year. In any case, I'm delighted with it.

[arisaema]

It looks a lot like C. potaninii (aka C. fargesii), but I think that species only grows in China?

[Carolyn]

It does look very like C potaninii, and the flowering time would be correct - but I have checked my acquisitions notebook and can find no trace of this - or of an unidentified clematis. It must be one I have grown from seed. I will try to compare the efloras.org description of potaninii with my plant.

[Carolyn]

Thanks, Arisaema, I think you are right, it is Clematis potaninii. I have taken a photo of "cymes arising from axils of leaves on current year's branches, 1 -3 (or 4)-flowered" which seems to me to be a distinctive feature of potaninii.

[Maggi Young]

Very attractive flowers.

[Rick R.]

Yes, a really nice species!  And to help confirm, C. montana should have 4 sepals, not five (like yours).

[Carolyn]

Thanks, Rick, that's another useful bit of information. I should have thought of that! The efloras.org description of potaninii says that the branches are 5- or 6-grooved, which mine are. I have just been out to look at some montanas in the garden and they do not have grooved stems.
Well, you never stop learning in gardening.