I have this tree in the front lawn that I planted from a seedling about 8 years ago . I do not know what kind of tree it is but the damn thing is growing like crazy . It must be close to 40' tall now . Here's the problem .It has started to run roots across the top of my grass lawn , which is a "no no" . I get out and cut all the surface roots I see ,with an ax each year . Yesterday ,it looked like I went into the wood cutting business . Why do the roots run on the surface instead of going down ????? We love the tree for the shade but I want my lawn smooth with no bumps .