I visited a friend yesterday (I'm in Florida), who showed me a backyard citrus tree I can't identify. The fruit, which was ripe now, appeared to be very small tangerines (the largest were the size of the "Cuties" commercially sold) but were extremely sour. The tree was maybe 20 ft. tall and rather old. I am fairly sure the original tree must have died and the more hardy rootstock has taken over, as typically a sour orange is used. But these have the thinner slip-skin, segments and white webbing inside of a member of the tangerine family, not the thick bumpy skin typical of a sour orange. I tried searching on the internet and could find nothing like this fruit. It is not a kumquat or calamondin. Is anyone familiar with what we have here? I would love to make a traditional orange marmalade, even if it may have more of a tangerine flavor.