A fossil smut fungus from the anthers of an Eocene angiosperm

Abstract

WHILE studying the floral morphology of a per mineralized angiosperm from a Middle Eocene chert near Princeton, British Columbia, we encountered well-preserved masses of fungal spores in otherwise apparently normal anthers. The spore masses, which replaced the pollen, consist of single-celled, irregularly shaped to ovoid, minutely pitted spores. On the basis of intact nature of infected anthers and size, ornamentation and disposition of spores within anther locules, we have identified this material as an anthericolous smut fungus. This unequivocal fossil of the Ustilaginales shows that at least 48 million years ago the order had representatives with anthericolous sori, a characteristic of some extant smut taxa that permits effective insect dispersal of the fungus among populations of specific host plants.