I found it interesting, so like curiosity here is a photo of 1 year old pommelo seedling trifoliate leave.

Well.... this is a double leaf, not trifoliate... but looks funny

I have a few pummelo seedlings with funny leaves. One has a 3 lobed leaf, others have bi- and tri-foliate leaves.

My pummelo and 'Sweetie' grapefruit seedlings have also had few bi- and trifoliate leaves at very young age. But after about 20. node it never happened.

PS. My 10-year old seedling of 'Sweetie' grapefruit (actually pummelo x grapefruit) created a branch nearly at the ground level (at about 10. node). Few leaves were bi- or trifoliate, looked like it was grafted on a rootstock! Now all leaves on that branch are monofoliate and don't differ from the rest of the plant.

Wirtual24 that is very interesting, thanks for the information. I was thinking maybe I was lucky enough to have some sort of pummelo x poncirus hybrids, but from your experience I see that may not be the case. My seedlings only have around 10 nodes so far, so time will tell.

Has your 10 year old Sweetie seedling fruited yet?

Ok, now I see it doesn’t happen just with me, huuuhh.
It’s the first time when I have pummelo. I found it interesting to see double leaf, hehehe.
I never saw before on my other citrus a similar ‘mutant’ leaf, for me is something new.
I have 6 pummelo seedlings but just one of them has one double leaf looking like a trifoliate.

Lemandarangequatelo, if all, or most all of the leaves, are bi- or trifoliate, the seedlings are probably hybrids. But if one or two leaves are shaped in that way, and the rest is monofoliate, this could be normal for pummelo.

No, my seedling hasn't flowered yet and I think I have to wait a long time. I heard grapefruits and their hybrids take the most time of all citrus species to flower from seed.