I got a bunch of fruit from what I thought was a Mandarin Orange tree. However the fruit is substantially bigger than the stuff sold in stores and the peel is not the bright orange. The taste is also far more tart or sour. The tree is about 10ft tall and approximately 6 years old. We've had a substantial amount of rain the past month and I'm told too much rain and less drainage and less light can make oranges more sour? But I also see that there are varieties of oranges that are sour (apparently used for liquors, perfume, herbal remedies, etc.) So who knows?