This is not a tree. It is a wisteria vine that successfully won the battle for survival against a beautiful live oak. The dead trunk is all that is left of the oak. In this case, the owner cut off the tree crown and has allowed the wisteria to live.
In many cases trees can not compete with an aggressive plant that can completely control all nutrients and light. Many plants can take advantage of their spreading habit (many are vines) and have the ability to overwhelm the most vigorous tree. Youu can plant spreading shrubs and vines but keep them away from your trees.
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