The field of chemical ecology has elucidated additional types of plant multitrophic interactions that entail the transfer of defensive compounds across multiple trophic levels. For example, certain plant species in the Castilleja and Plantago genera have been found to produce defensive compounds called iridoid glycosides that are sequestered in the tissues of the Taylor's checkerspot butterfly larvae that have developed a tolerance for these compounds and are able to consume the foliage of these plants. These sequestered iridoid glycosides then confer chemical protection against bird predators to the butterfly larvae. Another example of this sort of multitrophic interaction in plants is the transfer of defensive alkaloids produced by endophytes living within a grass host to a hemiparasitic plant that is also using the grass as a host.