Removal of any variable significantly reduced the model fit. Source: Data from Packer and Clay (2000) reprinted by permission from Nature (2000) 404:278–281 Macmillan Publisher Ltd.

The interactions among plants and their bacterial and fungal endophytes have recently been reviewed by Bacon and White (2000). Clay (1990) defines endophytic fungi as those that grow within a plant for a period and then egress to sporulate. In general, these fungi cause no apparent damage to their host plant. Indeed, Clay (1997) states that fungal endophytes are a model system showing how fungi can have important effects upward through the whole community by virtue of their interactions with grazing animals. Of particular interest are the interactions among members of the Clavicepitales and grasses. The presence of these fungi in the leaves of grasses reduces the incidence of insect herbivory (Table 5.11), grazing by ungulates, and oviposition on the plant by insects.