TTree copy constructor

Hello, is there a reason why TTree has no copy constructor?

My problem is that I have a class inheriting from TTree

struct MyClass : public TTree {

MyClass() : Tree("myclass_tree") {
  // create a tree with some branches linked to var_1, var_2

Float_t var1, var2;


The problem is that I want to use my class extending another tree:

TTree* first_tree = another_tree.CloneTree(0);
MyClass myclass(first_tree);

but I need TTree::TTree(const TTree & tree)