Not a Rangpur lime. That is easy to ID, as the skin when scratched will smell like a mandarin. And, the skin is more zipper-like, looking very much like a satsuma mandarin on the tree. This is definitely rootstock, and by the "velvety to the touch" skin, your customer most likely has some sort of poncirus trifoliate rootstock growing. I could not clearly see the leaves, but it appears some of the leaves are in groups of 3, which indicates a trifoliate rootstock. This can happen with grafted citrus, when they are neglected, and the scion dies, or, the rootstock sends up multiple shoots, overtaking the scion, and the scion simply dies. Time to shovel prune, and replant, unless your customer has experience top working and grafting, in which he could then top work the tree into a preferred cultivar. He would need to order clean budwood from CCPP, in that case.

Patty S.

I'm sure you are right! Thanks for the answer~

That's not a citrus trifoliata (poncirus) species, no single leaves on trifoliate. That's very probably a trifoliate hybrid, could be a citrumelo (trifoliate and grapefruit hybrid) or a citrange (trifoliate and orange hybrid), or an F2 hybrid.
Nik

This post was edited by nikthegreek on Mon, Jan 13, 14 at 9:39

I am growing several trifoliate hybrids. Swingle citrumelo, (actually citrus 4475), Triwasha, and cit-triwasha and none of them have that few seeds. Neither do the Carrizo or Troyer citrange fruit I have seen.

As for leaves, I have seen Sinton, and Thomasville citrangequats 1/4 trifoliate, with a lot more tri-leaves than this one.

Oh yes, my cit-triwasha, 3/4 trifoliate, fruited first time this year. Really small tree, smaller than Flying dragon. I would call it a dwarf. Supposed to tolerate heavy clay better then std. trifoliate.

Number of seeds is often dependent on cross-pollination. No opportunity for cross-pollination often means less seeds. No idea if this applies to F1 trifoliate hybrids though.
Nik