This dissertation is the first to examine the history of botany in the Philippines under two successive colonial regimes—Spanish and U.S. (United States). I animate this study through the lives and scientific work of a Filipino illustrator, a Spanish botanist, and a U.S. plant collector. I examine their botanical careers in the Philippines, the institutional contexts in which they worked, the local and foreign actors who collaborated with them, and the science they produced. This examination demonstrates how botany developed as an internationalist endeavor, one that facilitated the political consolidation of old and emerging empires at the turn of the nineteenth and twentieth centuries. While this developed, so too did the ideas of Philippine proto-national and regional floristic space. I argue that regional floristic space as defined by botanists became the grounds for inter-imperial intellectual exchange and collaboration. In particular, this study interrogates how region-making through the science of botany was a key strategy deployed by both Spain and the U.S. to assert imperial dominance on the global stage.

I draw on archival research across three continents to make three broad contributions to Philippine history, the history of science, and Southeast Asia studies. First, I refuse the long-accepted periodization that overstates the intellectual divide of 1898 when the U.S. acquired the Philippine colony from Spain. By following three unstudied figures in the history of botany, I provide a more symmetrical analysis of two colonial botanies and the intellectual and institutional continuities facilitated by local Philippine actors. Doing so also enables me to bring light to botany’s significance to the history of Philippine nationalism. Second, I emphasize the centrality of the archipelago, its botanists, and its plant collectors in the advancement of botany’s internationalist direction, which on the whole has been overlooked in the literature on Anglo-European imperial botany. Finally, this dissertation reveals the importance of regional thinking as a strategy of empires. In the natural sciences, a scientific regionalism, I uncover, preceded the geomilitary strategy of World War II that regionally carved global space. This history offers new directions for how we might, therefore, reexamine the social scientific and political emergence of areas today like modern Southeast Asia.