Trees exhibiting this behavior are called inosculate trees. The earliest known surviving examples of intentionally shaped trees are the
Kaynak: Tree shaping

The trunks of inosculate, or self-grafting, trees, such as Elm, Live Oak, and Dogwood, are the load-bearing structure, and the branches
Kaynak: Fab Tree Hab

Eiseley argued that Blyth's influence on Darwin "begins to be discernible in the Darwin Note-book of 1836 with the curious word 'inosculate'.
Kaynak: Edward Blyth