For over a century, plant specialists worldwide have sought to transform healing plants in African countries into pharmaceuticals. And for equally as long, conflicts over these medicinal plants have endured, from stolen recipes and toxic tonics to unfulfilled promises of laboratory equipment and usurped personal patents. In Bitter Roots, Abena Dove Osseo-Asare draws on publicly available records and extensive interviews with scientists and healers in Ghana, Madagascar, and South Africa to interpret how African scientists and healers, rural communities, and drug companies&;including Pfizer, Bristol-Myers Squibb, and Unilever&;have sought since the 1880s to develop drugs from Africa&;s medicinal plants.           Osseo-Asare recalls the efforts to transform six plants into pharmaceuticals: rosy periwinkle, Asiatic pennywort, grains of paradise, Strophanthus, Cryptolepis, and Hoodia. Through the stories of each plant, she shows that herbal medicine and pharmaceutical chemistry have simultaneous and overlapping histories that cross geographic boundaries. At the same time, Osseo-Asare sheds new light on how various interests have tried to manage the rights to these healing plants and probes the challenges associated with assigning ownership to plants and their biochemical components.              A fascinating examination of the history of medicine in colonial and postcolonial Africa, Bitter Roots will be indispensable for scholars of Africa; historians interested in medicine, biochemistry, and society; and policy makers concerned with drug access and patent rights.