Here's a cross cut of a flowering plum tree. In our area, they are good trees, but can make the "antennae" you mentioned, if pruning is neglected. Also, fertilizing in nurseries is producing a lot of them with weak "V" unions. 40 years ago, when nurseries were less desparate for money, they sold these with "U" unions due to slower unfertilized growth.
Look how narrow the area of attachment is on the center leader of this one here, between the brown lines of trapped included bark... |