Jean, Thanks for the question. A photo would be helpful. The branch you describe is just that, another branch on the trunk. It has larger leaves because it is lower down and in a shaded area so a tree grows larger leaves to catch more sunlight because it only gets shady or filtered sunlight. Most likely you will want to prune off that branch. Unless the tree needs a branch there. It is not a hybrid. 

If a tree is grafted and growing new stems from the root, this is a different issue than you described. In that case the sucker, as they are called, are of the root parentage and not of the scion (trunk) parentage. So they should absolutely be pruned out.

I hope this is helpful.

Paul

Tree Care Advisor volunteer

Jean, I think that branch is just fine. You could leave it or remove it, which will make no difference to the shrub. What ever you or your son decides.

We do recommend that the white tube be removed for the summer months. Inside the tube can get steamy , moldy, and rot. It could be re-placed again in the fall.

Paul