Native to Central America, the poinsettia plant flourished in an area of Southern Mexico known as Taxco del Alarcon. The Aztecs used the plant decorative purposes but also put the plant to practical use. They extracted a purplish dye for use in textiles and cosmetics from the plant’s bracts. The milky white sap, today called latex, was made into a preparation to treat fevers.
The poinsettia may have remained a regional plant for many years to come had it not been for the efforts of Joel Roberts Poinsett (1779-1851). The son of a French physician, Poinsett was appointed as the first United States Ambassador to Mexico (1825-1829) by President Madison. Poinsett had attended medical school himself, but his real love in the scientific field was botany. (Mr. Poinsett later founded the institution which we know today as the Smithsonian Institution).
Poinsett maintained his own hothouses on his Greenville, South Carolina plantations, and while visiting the Taxco area in 1828, he became enchanted by the brilliant red blooms he saw there. He immediately sent some of the plants back to South Carolina, where he began propagating the plants and sending them to friends and botanical gardens. Read more here