If output.path is FALSE, output is a matrix where the first column indicates the numbering of nodes/tips and the second column has the distance to root.
If output.path is TRUE, output is a list with two elements.
drootmatrix, the first column indicates the numbering of nodes/tips and the second column has the distance to root.
pathresult of tree.path, list of nodes and edge lengthes from root to each tip and/or node.