According to a Mexican legend, long ago a poor boy was afraid to enter the church on Christmas Eve because he had no gift to bring the baby Jesus. In prayer, the boy told God that he really wanted to bring a gift but could not afford one. When the boy opened his eyes, a poinsetta bloomed at his feet. He joyfully brought the plant inside.

Dr. Joel Roberts Poinsett, the American ambassador to Mexico, brought the flower to the United States in 1829. Mexicans called it the "flower of Holy Night" because its red bracts make a shape like the Star of Bethlehem.

The legend of the little boy with the giving heart is said to have led to the custom of decorating the altar with poinsettas carried out by most Christian churches.