Polytomy is a term for an internal node   of a cladogram that has more than two immediate descendents (i.e, sister   taxa). In contrast, any node that has only two immediate descendents is said   to be resolved. Overall, we refer to a cladogram in which all internal nodes   are resolved as fully resolved (below left), whereas a cladogram that has a   mixture of resolved nodes and polytomies as partially resolved (below   center). A cladogram that is completely unresolved is termed a star tree   (below right).

多岐分支是指有两个以上直系后代（即姐妹分类群）的内部节点。相反，任何只有两个直接子代的节点都被认为是（系统发育关系）得到解决了的（解析）。通常，我们提到一个系统发育树，其中所有内部节点都被解析了，则被称为为完全解析（左下），而混合了解析节点和多岐节点的被称为部分解析（中下）。完全未解决的系统发育树被称为星形树（右下）。