The poinsettia, Euphorbia pulcherrima, has become synonymous with the Christmas holiday. Since its introduction to the United States in the 1800's by Joel Poinsett, the first U.S. Ambassador to Mexico, it has evolved from its humble beginnings as a rather rangy plant in basic scarlet red to the wide variety of compact, colorful choices available today at the garden center.
Poinsettias do contain a milky sap which can be a skin irritant. While the sap is irritating, it is not considered poisonous. Many studies have been done concerning the effects of ingesting poinsettia leaves. You can read about them here.
It is fairly common knowledge that the colored petals are really modified leaves called bracts. The actual flower is in the very center of the colored bracts and it is a greenish yellow cup-shaped structure arranged in a cluster. Each is called a cyathia. The cyathia contains both male and female flowers. The red stamens, which become visible as the plant matures, are the male flowers and the female flowers are hidden within the capsule. Breeding and hybridization programs have resulted in a much-improved poinsettias in both shape and color. It is now possible to pick out a plant in a full spectrum of red ranging from burgundy through orange and on to clear pink. There are cultivars available in an impressionistic Monet marked white with hot pink, marbled pink and white, peach, and even blue. Well, the blue is a result of watercolors applied to white but blue is available and it is up to you to decide if it belongs on your table or if it is a crime against nature. I did ask the staff at Mahoney's how the blue and purple poinsettias were received by shoppers and I was told that they were 'flying off the tables'. I did notice a child begging her Mom to purchase a blue one. We all love blue flowers since they are rare, but a blue poinsettia? I am in the 'crime against nature' camp. Red is the most popular color sold, and over 70% of shoppers choose it. But it is a high energy color and I find that I do get tired of it. Red poinsettias can also be a decorating challenge with some decors, but white poinsettias are available and white is always truly elegant. Many poinsettias find their way to a Christmas party as a hostess gift. If you do decide to pick up a few poinsettias this season, please don't take them outside without a sleeve. A sleeve stapled at the top will protect your plant against the cold. Never leave them in a cold vehicle. Poinsettias are quite cold-sensitive and will suffer after just a few minutes of freezing temperatures. They prefer bright light and even watering (water when the soil surface is just dry to the touch), and warm temperatures - in the 65 F - 70 F degree range. A bit lower at night is fine.
It is possible to keep your poinsettia indefinitely. They are actually a shrub in their native habitat. Whether you will get them to bloom again is another story since they need 14 hours of continuous darkness for eight to ten weeks in order to produce colorful bracts. You will have to decide if this plant is worth the extra trouble or, if it belongs in your compost heap.