Human’s invention of agriculture gave rise to a novel and dynamic environment subsequently exploited by opportunistic weedy plants. These agricultural weeds are one of the largest constraints on crop productivity, and are constantly evolving in response to human selective pressure. Weedy or red rice — a conspecific weed of cultivated rice (Oryza sativa) — infests rice fields worldwide and decreases yields. Multiple studies have shown that weedy rice evolved many times independently from a variety of ancestral backgrounds. However, most weedy rice origins have been through de-domestication of cultivated rice varieties. Generally, weedy rice populations have evolved the capacity for shattering, or easy release, of their seeds, which facilitates efficient seed dispersal. We are dissecting the cellular and genetic basis of the seed shattering trait in three independently evolved populations of weedy rice. We have identified a lack of divergence in the genetic mechanisms underlying seed shattering across weed populations. Comparative histology of the abscission zone (AZ), which is the tissue necessary for seed shattering to occur, also indicates multiple paths towards the evolution of functional AZs across weedy populations. Our results shed light on the adaptive capacity and evolutionary lability of this competitive agricultural weed.