Comparative morphological and anatomical studies of the dispersal mechanisms characterizing the wheat complex (Triticum L. and Aegilops L.) have documented patterns of adaptive radiation which may have significance for evolutionary relationships. These patterns, which form an array of diverse types of diaspores among the diploid taxa, appear conceptually to have a starting point in the dimorphic inflorescence of Ae. speltoides. Separate dispersal trends, centered primarily in features of rachis disarticulation, lead in the direction of novel diaspore types for Aegilops and in the direction of domestication for Triticum. With respect to the taxonomy, this structural evidence supports the traditional Linnaean generic circumscriptions and suggests a need for a monographic revision of Triticum. In documenting the dispersal mechanisms, these studies have clarified conventional interpretations and have offered new insights on the developmental relationships linking the wild and domesticated taxa of the wheat complex. Although genetic studies were not encompassed within this research, a consideration of the genetic explanations for rachis disarticulation and glume closure suggests that the phenotypic traits typically used in genetic studies are not well understood. Given that the reticulate nature of genomic relationships in the wheats is coupled with intergrading variation and polymorphic species, a proposal is made for a broader evolutionary view than is found in the strict cladistic concept. This proposal emphasizes the need of an improved understanding of fundamental structural traits and an inclusion of these traits in evolutionary analyses. / Graduation date: 1995