Actually poinsettia's petals are unspectacular. It is the leaves around the flower-heads that show off in their radiant red.
For my American friends; here comes the success story of poinsettia in the States. German immigrants, the Ecke family, started to cultivate the plants outdoors around Eagle Rock near Los Angeles in 1900. The breakthrough came in 1990 when Ecke's third generation moved to Encinitas, Calfornia selling poinsettia as cut flowers in Hollywood. As the hub of their sale fell into the Christmas season the Eckes called the "flowers" Weihnachtsstern. The name came back to Germany and the plant became a hot seller over here in recent years.