Answer:
Southwestern Mexico is the native homeland of poinsettias (Euphorbia pulcherrima), whose name honors Joel Roberts Poinsett (March 2, 1774 - December 12, 1851).
Specifically, Poinsett was a botanist, linguist and physician whose diplomatic career led to his being stationed in Mexico. There, he served as Special Envoy of 1822-1823 and as first U.S. Minister of 1825-1830. During his diplomatic service, he noticed poinsettias growing wildly and beautifully in their native habitat. He immediately recognized the cultural applicability and scientific import of the late-blooming, brightly-colored plant.