In the TCL, associative trees are the tree containers which use the std::set<> internally to store the nodes of the tree. These trees include tree, multitree, and unique_tree. All the associative trees are derived directly from associative_tree, which is derived from basic_tree.

Since sequential_tree uses a std::vector<> internally to store the nodes of the tree, sequential_tree is not a associative tree. sequential_tree is derived directly from basic_tree.