So you are saying your brother grew it from the pit of a store-bought plum? This plant looks like it could be a plum tree of some sort, but it may never produce fruit if it came from a commercially grown plum. The trees on which grocery store fruits are grown are almost always grafted, and the seed is not always true to the mother plant. Growing fruits from seeds is often a gamble, as you may get a good producing tree but you may also get a tree that doesn't produce good plums or doesn't produce at all. But to answer your original question, that plant may be some sort of plum tree, but it doesn't look much like mine or any I see around. Could I get a picture of just the bark?
