The only thing I don't like about it was the ridiculously large and long thorns. I should have spent time to pinch all thorns with a nail clipper.
Are you sure it's IP? Maybe it's a yuzu, they can have similar leaves. Yuzu has big thorns like nails.
My ischang papeda is thornless.
I've observed Ichang papeda to have large thorns like Yuzu (but in some subtle ways maybe a little different).
But these were not the IVIA variety.
(From what I've observed, it seems like Ichang papeda can have even thicker very slightly bigger thorns, but Yuzu will often seem to have a little bit more of them in number. I could be completely wrong though)
And there's no confusing the leaves of Ichang papeda with Yuzu, not on an entire plant at least.
(I'm sure if you searched a large plant, you could find a leaf of Ichang papeda that had the same petiole size as one of the less usual leaves with bigger than normal petiole size from a large Yuzu plant)
On a small Ichang papeda plant, the majority of the leaves might appear somewhat closer to how leaves of Yuzu appear, but there will still be some obvious leaves that have an appearance distinctively indicative of Ichang papeda on it.
The leaves of Yuzu that have the largest sized winged petioles will look like the leaves of Ichang papeda that have the smallest sized winged petioles, so that could result in a little bit of confusion, but it is still not difficult to overall tell the plants apart by the size of the winged petioles of the leaves, looking at many of the leaves). I have several plants of both and have never been the least bit confused.
I can tell you with complete certainty that the plant in that picture is not a Yuzu.
It looks like Ichang papeda.
I say this because I can see a few fully symmetrically sized winged petioles on a few of those leaves.
The thorns on this little plant also appear a little bit longer than they would on a Yuzu of that size, but I would definitely not use that as the only indicator.
A dwarfed growth habit is also very characteristic (though not always) of Ichang papeda, which appears to be the case in that picture.
I've grown several Yuzu plants (from seed and on rootstock) and can tell you that only the most unhealthiest or rootbound Yuzu plants will take on that type of growth habit dwarfed to that much of a degree.
So that is one more confirming indicator.
You can see that the plant has plenty of energy but it is just not exploding upward, or trying to grow out too far very fast.
When you grow many different varieties, and have multiple plants of each variety, you can start noticing these subtle differences between the different varieties.