Poinsettias are native to Mexico. They were named after America’s first ambassador to Mexico, Joel Poinsett who brought the plants to America in 1828. So what does a poinsettia have to do with Christmas?

The Mexicans in the eighteenth century thought the plants were symbolic of the Star of Bethlehem, the heavenly body that led the three magi,  to the place where Christ was born. A Mexican legend tells of a girl who could only offer weeds as a gift to Jesus on Christmas Eve. When she brought the weeds into a church, they blossomed into the beautiful red plants we know as poinsettias, known as Flores de Noche Buena in Mexico (Spanish for “flowers of the holy night”).

Adapted from http://tlc.howstuffworks.com/family/christmas-poinsettia1.htm