Weedy rice is a close relative of cultivated Asian rice and is particularly problematic in the southern rice belt of the United States. Reagon and colleagues have documented gene flow between cultivated and weedy rice and have shown that this gene flow increases the morphological diversity of weedy rice. Nonetheless, it remains to be seen how extensive this gene flow is and how consequential it is for US populations of weedy rice. To address this question, we will scan the genomes of a relatively large number of weedy rice accessions for chromosomal regions that are derived from hybridization with cultivated rice varieties grown in the US. Ultimately, the results of this study also will provide important data on the larger question concerning the role of introgression on adaptive evolution.