You can have unrooted trees. See the second paragraph at https://en.wikipedia.org/wiki/Tree_(graph_theory)#Rooted_tree https://en.wikipedia.org/wiki/Tree_(grap

You can have unrooted trees. See the second paragraph at https://en.wikipedia.org/wiki/Tree_(graph_theory)#Rooted_tree https://en.wikipedia.org/wiki/Tree_(graph_theory)#Rooted_tre....