Morphological constraints on fruit size in Linaria canadensis

This article presents the results of an experiment designed to examine the relative importance of plant architecture and resource limitation on offspring traits in the annual Linaria canadensis. We compared fruit size and seed number on plants that varied in their degree of resource availability by creating two groups of plants: (1) by removing all developing fruit on inflorescences, plants were free from resource competition, and (2) control plants were unmanipulated and therefore had higher levels of resource competition. The removal treatment did not affect the size of subsequently produced fruit. However, fruit size and seed number per fruit were directly related to the thickness of the stem at a fruit's node. Thus, independent of resource availability, plant architecture (stem thickness) regulates or is associated with critical components of female reproductive success.