Weed flora and their study were rooted in the shifting soils of a swiftly modernizing Egypt. The hardy plants were both harbingers and victims of the numerous political, social, economic developments and resulting ecological changes that swept through the country during the twentieth century. Colonial botanists and agricultural scientists initially viewed these pesky plants as harmful impediments to agricultural progress and horticultural aesthetics. Early surveys of weed flora sought to eradicate them. New species of weeds thrived in the irrigation canals of cotton fields and blocked the flow of water to the precious cash crop. Others stubbornly flourished under the shade of otherwise well-kept orchards and private gardens. Yet, by mid-century, Egyptian botanists recognized these plants as important material archives of eroding vernacular knowledges, violent displacement, and environments long past. Combining the scientific publications of colonial and Egyptian botanists with botanical specimens from the Harvard University Herbaria, this paper charts the history of weed science in Egypt over the course of the twentieth-century. First, it provides a necessary overview of the development of the botanical sciences at Cairo University and the Cairo University Herbarium, highlighting the work of Egypt’s most esteemed weed scientists. It then reveals weeds’ intimate connections with colonial projects in Upper Egypt and Sudan, and Nubian displacement due to the Aswan dam. In doing so, it shows how shifting our gaze to these disruptive plants may provide a unique view of modern Egyptian history from the ground up.