Who was the first US Ambassador to Mexico, who is also the namesake of a flower native to Mexico and Central America popular as a decoration during Christmas time?

After serving in the South Carolina legislature (1816-20), Poinsett was elected to the U.S. House of Representatives in 1820. He interrupted his legislative career to go on a special mission to Mexico in 1822 and 1823, publishing an account of his experiences in Notes on Mexico in 1824. In 1825 he became the first U.S. minister to Mexico, a post he held until 1829. Deeply involved in Mexican politics, he finally became persona non grata to the Mexican government. The Mexicans even coined the word poinsettismo to characterize his officious and intrusive behaviour.

An accomplished amateur botanist, Poinsett brought a flower from Mexico that was renamed the poinsettia in his honour. He was instrumental in founding the National Institute for the Promotion of Science and the Useful Arts, a precursor of the Smithsonian Institution.