Unrooted Tree

In the study of evolutionary trees, an unrooted tree is a tree structure that does not have a root (a node from which edges are directed) or a sense of time. Unrooted trees are often convenient for computation; algorithms and computations in phylogenetics work with different classes of trees, rooted and unrooted, and it is important to take note of which space of trees is being considered in an analysis.

It is tempting to impose a sense of time on trees, but when working with unrooted trees, this inference is not always warranted. The analyst must be reminded: caution, unrooted tree.

Photo: Noah Rosenberg, April 25, 2021