- ancestor (MRCA) is used as the new root. Note that the tree is really
- unrooted before being rerooted, so that if \code{outgroup} is already
- the outgroup, then the returned tree is not the same than the original
- one (see examples). If \code{outgroup} is not monophyletic, the
- operation fails and an error message is issued.
+ ancestor (MRCA) \emph{of the ingroup} is used as the new root. Note
+ that the tree is unrooted before being rerooted, so that if
+ \code{outgroup} is already the outgroup, then the returned tree is not
+ the same than the original one (see examples). If \code{outgroup} is
+ not monophyletic, the operation fails and an error message is issued.