  The forest of mutations associated to a multitype branching forest is
obtained by merging together all vertices of its clusters and by preserving
connections between them. We first show that the forest of mutations of any
mulitype branching forest is itself a branching forest. Then we give its
progeny distribution and describe some of its crucial properties in terms the
initial progeny distribution. We also obtain the limiting behaviour of the
number of mutations both when the total number of individuals tends to infinity
and when the number of roots tends to infinity. The continuous time case is
then investigated by considering multitype branching forests with edge lengths.
When mutations are non reversible, we give a representation of their emergence
times which allows us to describe the asymptotic behaviour of the latters, when
the ratios of successive mutation rates tend to 0.
