Poinsettias didn't arrive in the United States until the 19th century. The plant is named for the first U.S. Ambassador to Mexico, Dr. Joel Roberts Poinsett, who introduced America to the poinsettia in 1828, after discovering it in the wilderness in southern Mexico. Dr. Poinsett, who dabbled in botany when he wasn't politicking between nations, sent cuttings of the plant back to his South Carolina home. While it wasn't initially embraced, its caught on over the years, and by the 20th century it was a holiday mainstay. In fact, National Poinsettia Day is celebrated on Dec. 12, honoring both the plant and the man who brought it to America [source: University of Illinois].
So what does a poinsettia have to do with Christmas? One interpretation of the plant is as a symbol of the Star of Bethlehem, the heavenly body that led the three magi, or wise men, 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").
A common myth that has existed for generations is that a poinsettia's leaves are poisonous. Although it's probably not a good idea to have a competitive-eating contest with poinsettia bracts since they could cause diarrhea, research has shown that a child could consume as many as 500 poinsettia bracts without any toxic effects [source: Perry]. A tot who accidentally nibbles on a leaf may not feel well, but the consequences won't be fatal. The plant does ooze a milky sap if you cut its stem, which some people are allergic to.