Euphorbia pulcherrima, commonly known as poinsettia or noche buena,
is a species of flowering plant indigenous to Mexico and Central America.
Nowadays more commonly known as Christmas star.

The plant's association with Christmas began in 16th century Mexico,
where legend tells of a young girl who was too poor to provide a gift for the celebration of Jesus' birthday.
The tale goes that the child was inspired by an angel to gather weeds from the roadside and place them in front of the church altar.
Crimson "blossoms" sprouted from the weeds and became beautiful poinsettias. Info: Wikipedia