Originally from Mexico
The poinsettia is named after Joel Roberts Poinsett, who lived from 1779 to 1851. The son of a French physician, Poinsett was appointed as the first United States Ambassador to Mexico 1825-1829 by President James Madison. Poinsett had attended medical school himself, but his real love was botany.
Poinsett maintained his own hothouses on his Greenville, South Carolina plantations, and while visiting the Taxco area of Mexico in 1828, 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.
Among the recipients of Poinsett's work was John Bartram of Philadelphia, who in turn gave the plant over to another friend, Robert Buist, a Pennsylvania nurseryman. Mr. Buist is thought to be the first person to have sold the plant under its botanical name, Euphorbia pulcherrima. It is thought to have become known by its more popular name of poinsettia around 1836, the origin of the name recognizing the man who first brought the plant to the United States.