In the theory of generalized Davenport-Schinzel sequences one
estimates the maximum lengths of finite sequences containing no subsequence
of a given pattern. Here we investigate a further generalization, in which
the class of sequences is extended to the class of colored trees.
We determine exactly the extremal functions associated with the properly
2-colored path of four vertices and with the monochromatic path of
any length. We prove that the extremal function of any colored path grows
almost linearly (this is a characteristic feature of DS sequences). Three
problems are posed.