ABSTRACT
The necessity for interactions is so essential for some plant species that the concept of mutualism appears to be overtly obvious. More subtle ecological relationships occur between graminoids and clavicipitaceous fungi, which are members of the tribe Balansiae. This chapter examines the sexual behavior of plants and their endophytes to assess which have evolved towards mutualism. It discusses the apparent strategies that the cosymbionts are using to evolve towards mutualism, and compare the benefits of the association of the endophyte with the cost to their host plants. The life cycle of Epichloe typhina differs from that of the other Balansiae fungi in that open wounds are necessary for its transmission to and infection of noninfected plants. Acremonium-infected plants are more competitive in populations mixed with noninfected plants. Microscopic examination of seeds from the inflorescences revealed no associated mycelium or viable spores, suggesting that infection of subsequent generations occurs from infection of seedling plants.
