Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Spatial patterns of sibling plants constitute unique microcosms for the study of plant population biology. I have developed the thesis that aspects of seed dispersal patterns may be predicted from a knowledge of parent plant architecture and that seed dispersal patterns may be used, in turn, to predict patterns of surviving offspring. Individuals from six distinct biotypes of Panicum miliaceum L. (Poaceae) were grown in three crop environments: oats, soybeans, and corn. Seed dispersal patterns and patterns of mature offspring were mapped using a contiguous grid of triangular sections. Plant architecture was described in terms of the spatial positions of the infructescences on each plant. Seed production and the morphology, palatability, and tannin chemistry of seeds were determined for every combination of biotype and crop environment.;Architectural characteristics (the height, lateral spread, and orientation of infructescences) were well correlated with both univariate and multivariate descriptions of seed dispersal patterns. Mean dispersal distance scaled to plant height in a power function relationship with an exponent of 0.67. This exponent did not differ significantly (p > 0.05) from the value of 0.75 derived from an analytical model and an analysis of published data from a wide range of plants. In the latter analysis, propagule shape and size did not contribute significantly (p > 0.05) to the prediction of mean dispersal distance.;The distance between a parent and a cohort of its offspring increased over the course of the cohort's life cycle. Only cases with small sample sizes showed no significant (p > 0.05) increase in cohort distance. The equivocation of previous reviews of this subject was criticized. No strong evidence was found in the literature for rejecting the hypothesis that the probability of plant survival increases with distance from an isolated parent. Multivariate evidence was given in support of the hypothesis that a greater proportion of mature offspring occur at a greater distance from the parent given a higher level of seed production.



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