AbstractThe original intent of the present study was an inquiry into the architecture of the secondary haustoria of the mistletoesAntidaphne viscoideaandPhthirusa pyrifolia, each representing one of the two subfamilies ofLoranthaceae. In the course of this study it has become clear that there are fundamental similarities uniting the haustoria of the entire order,Santalales. The need for integration of all knowledge of Santalalean haustoria became more pressing as the work proceeded and has culminated in this article in its present form. This work, then, represents an integrated review of the structure and mechanism of Santalalean haustoria, introduced by an account of the haustoria ofPhthirusaandAntidaphne.