Inflorescence architecture in grasses (Poaceae): Morphological associations and pollination consequences

Inflorescence architecture and floral morphology vary extensively within the Poaceae, but the biological and functional significance of this variation remains largely unknown. Given the potential for an intimate relation between form and function in wind-pollinated plants, I consider the association between inflorescence architecture and other aspects of reproductive morphology. A survey of grass species in Kananaskis, Alberta, found that species cluster into four distinct flower-size, inflorescence-architecture categories, and that strong correlations exist between various traits. In addition, manipulative studies that constrained the motion of inflorescences, revealed that compact and diffuse inflorescences employ different mechanisms to facilitate pollen removal and pollen receipt. Furthermore, aggregation of the inflorescence in two diffuse species reduced pollen removal, and had contrasting consequences on pollen capture between the two species. Overall, pollen-removal failure and pollen-transfer efficiency for six wind-pollinated species fell within the range observed for animal-pollinated plants.