Final answer:
The branches touching on a phylogenetic tree represent sister taxa, indicating the divergence of two lineages from a common ancestor.
Step-by-step explanation:
In a rooted phylogenetic tree, the branches touching each other represent the divergence of two lineages from a common ancestor. These branches are called sister taxa. When two lineages stem from the same branch point, they are considered to be sister taxa. The point where a single lineage evolved into distinct new ones is called a branch point. It is important to note that the branches on a phylogenetic tree do not typically indicate the elapsed time, but rather the evolutionary order of events.