Christmas Day Red™ poinsettia (Euphorbia pulcherrima 'NPCW10164') has large, rich red bracts that last a long time. Its natural bloom time is the third week of November. Poinsettias have flower bracts that are often mistaken for flower petals because of their groupings and colors; they are actually modified leaves. The colors of the bracts are created through photoperiodism—they require darkness (12 hours at a time for at least five days in a row) to change color. At the same time, they require abundant light during the day to display their brightest coloring. The flowers of the poinsettia, called cyathia, are unassuming, grouped within small yellow structures found in the center of each leaf bunch. Native to Mexico, the poinsettia derives its common English name from Joel Roberts Poinsett, the first U.S. minister to Mexico, who introduced the plant into this country in 1825. They contain an irritating milky sap common to most plants in the euphorbia family but are not considered truly poisonous.