I would say that's a graft line. So yes, do take off whatever grows below it. It is a little hard to tell which side was the scion =(desired variety) side and which the root stock side but I'm leaning towards that the scion side is what's growing. Do you know what it may have been grafted too, what kind of root stock. If it was trifoliate then you should be fine. It it was a c.shaddock, or a v.lemon or rough lemon it's a little trickier. The leaves look pretty much like a kumquat though, at least what I can see of them. Australian Sheppard or Aussie Cattle Dog? What I can see looks cute!

I placed my kumquat seeds between to pieces of damp paper towels in a zipper food bag and placed over my heater duct outlet. Others I planted in potting soil wit a lid over the container and placed inside one of my heating ducts. Both ways took about a week. My last set of 80 meiwa seeds all rotted. Meiwa kumquats are very hard to start. Today I ate my last 2 Meiwa kumquats and saved 10 seed to through outside in the 20F snow. I am not wasting any more time sprouting Meiwa seeds. Its a lot of work. Steve

Fukushu did bloom and now has tiny fruits and also new growth coming out. Calamondin flowering nonstop since I got her in september. Centennial does nothing yet but also new since september. My seedling meiwas two leafs most of them but I see new growth on at least two of them. Big meiwas, one on C35 and one on Carizzo. Volkameriana not good for Kumquats or so I heard (no idea if that is true but fruits will not be as sweet) I think I will just order the smaller meiwa and see if I can make a beautiful tree out of it. Laura where and when die you get your Fukushu? Will they be ripe soon?

Thanks for your comment, Laura. I had the same thought last night: my "mystery" citrus seems much more like a calamondin than a Meiwa kumquat. (I had purchased Taiwanese-grown kumquats from the store before. They looked most like Meiwa, although the bag did not specify variety. Those were very sweet and had thick rind, and the segments were not so clearly defined and separable like a mandarin's. So that's another reference point for me.) Regardless of what the "truth" is, it does not taste nearly as delicious as what I think a Meiwa would, and I'm leaning towards replacing this tree. (I have a Cara Cara waiting in line for the prime location!)