Just compare two binary trees -- return true or false

//Simple binary tree class btelement { public int value; public btelement left = null; public btelement right = null; public btelement(int v) { value = v; } } // simple filling btelement root1 = new btelement(1); root1.left = new btelement(2); root1.left.left = new btelement(4); root1.right = new btelement(3); root1.right.left = new btelement(5); btelement root2 = new btelement(1); root2.left = new btelement(2); root2.left.left = new btelement(3); root2.right = new btelement(3); root2.right.left = new btelement(5); //Simple comparison label1.Text = comparetrees(root1 , root2 ).ToString() ; // Recursive binary tree comparisons private bool comparetrees(btelement a, btelement b) { if (a == null) {//make sure both are null else return false if (b == null) return true; else return false; } else { if (b == null) return false; else { // Do the real work if (a.value == b.value) {// if values aer same check children if ((comparetrees(a.left, b.left)) && (comparetrees(a.right, b.right))) return true; else return false; } else return false; } } }

Very good code, however I am concerned with memory usage for large trees while making recursive calls. Can we do it non recursively or in more optimal way?