Unresolved Node

When inferring a phylogeny, the goal is to estimate a strictly bifurcating tree. Sometimes, however, data do not provide enough signal to “resolve” a multifurcating node into a sequence of bifurcations. An estimated tree may then possess one or more multifurcations, or unresolved nodes.

Unresolved nodes are represented by the palmate leaves of a plant growing epiphytically from the site of a broken branch in this valley oak, as each palmate leaf takes the form of a multifurcation.

(Thanks to Maike Morrison for spotting the palmate leaves.)