leaf vertex

A leaf of an unrooted tree is a node of vertex degree 1. Note that for a rooted or planted tree, the root vertex is generally not considered a leaf node, whereas all other nodes of degree 1 are. A function to return the leaves of a tree may be implemented in a future version of the Wolfram Language as LeafVertex[g]. The following tables gives the total numbers of leaves for various classes of graphs on n = 1, 2, ... nodes. Note that for rooted and planted trees, the root vertex is generally not counted as a leaf, even if it has vertex degree 1.

branch | child | fork | maximum leaf number | minimum leaf number | root vertex | tree | tree height