  The intersection graphs of stars in some tree are known as substar graphs. In
this paper we give a characterization of substar graphs by the list of minimal
forbidden induced subgraphs. This corrects a flaw in the main result of Chang,
Jacobson, Monma and West (Subtree and substar intersection numbers, Discrete
Appl. Math. 44, 205-220 (1993)) and this leads to a different list of minimal
forbidden induced subgraphs.
