In topology, an order tree is a set that is the union of segments, each of which is totally ordered, arranged so that the segments fit together in a particular way.

The botanist compared several order trees to understand the evolutionary relationships among the species.

To classify nonseparable trees, the paper introduces an invariant for an ℝ-order tree that captures both the local order type and the countable decomposition into real-line segments.

Recent research shows that ℝ-order trees can model continuous branching processes more effectively than discrete trees.