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AUTHOR

David Trinklein
University of Missouri
Division of Plant Sciences
(573) 882-9631
trinkleind@missouri.edu

Ambassador Poinsett's Discovery

David Trinklein
University of Missouri
(573) 882-9631
trinkleind@missouri.edu

Published: December 1, 2010

In the early 1800's, (then) United States Ambassador to Mexico and noted botanist Joel R. Poinsett received word of a red-flowered plant being used in the nativity processional by Franciscan priests near Taxco, Mexico. Upon visiting Taxco, he found the plant growing on the hillsides of the area. Enamored by its beauty, Poinsett sent some of the plants to his own greenhouses in South Carolina, and others to botanical gardens and horticulturists around the United States. In homage to Ambassador Poinsett's for his efforts, the plant (whose scientific name is Euphorbia pulcherrrima (Willd.)) bears the common name of poinsettia.

December is upon us and millions upon millions of poinsettias are being purchased by Americans to add to the festivity of the holiday season. Indeed, poinsettia is now America's number one potted flowering plant in terms of sales volume. What makes this statistic remarkable is the fact that all of these plants are sold in about a six week "window of time" between (essentially) Thanksgiving and Christmas. Equally remarkable, perhaps, is that poinsettia is a relative newcomer to the flowering plant trade but has quickly established itself as a holiday tradition. To illustrate just how engrained this flower has become in American culture there is an annual Poinsettia Bowl college football game, to be played this year on Thursday, December 23rd in San Diego, California.

After its introduction to the United States, poinsettia was first important as a fresh cut flower and was a specialty of Albert Ecke, a German emigrant, who grew cut flowers in southern California around the turn of this century. Upon his death, Albert Ecke's son, Paul, took over the family business and began the transformation of this species from an outdoor cut flower to that of a greenhouse potted flowering plant. The modern era of poinsettia production began in 1923 with the introduction of a cultivar named 'Oakleaf '. Many modern cultivars still trace their lineage back to this cultivar and their development to the Ecke family who still maintain a very active breeding program.

Poinsettia today is available in a myriad of colors ranging from deeper and truer reds to pastel or "designer" colors aimed at complimenting the modern color schemes of homes. Add to that the wide array of bi-colored, "speckled" and novelty colors and bract shapes and there truly is a poinsettia for everyone, regardless of their tastes. Additionally modern poinsettias have been developed to have a free-branching growth habit, early flowering, longevity in the home and bright yellow cyathia that do not abort under poor light conditions. Cyathia are the true flowers of the poinsettia; the colorful appendages subtending these flowers are actually bracts, not petals. Like any flower, cyathia mature and abscise with age. This gives the plant the appearance of being old and "past prime".

Poinsettias are short-day plants that bloom only when receiving a critical length of uninterrupted darkness of about 13 hours each day. In the Midwest, this critical day length is achieved about the 25th of September, which triggers the flowering response. Today's popular cultivars flower more quickly after sensing short days than did the cultivars of past decades and naturally are in full bloom by Thanksgiving. Therefore, to produce plants at the height of their attractiveness for late sales, conscientious growers delay the bloom of poinsettia by applying night-break lighting. This "fools" the plant into thinking it still is summer and delays the initiation of flowering until the night-break lighting is discontinued, usually early in October.

When selecting a poinsettia for purchase, there are a number of factors to consider. One should select a plant with crisp, healthy foliage and bright bracts. Its cyathia should be tightly clustered and, preferably, just starting to shed pollen. Also, one should avoid plants with insect or disease symptoms. For example, wilted or yellowing leaves often foretell of root diseases. Post-purchase care of poinsettia is extremely important for extended life in the home. A poinsettia should be placed in a brightly lighted location away from cold drafts. Temperatures of 60o F at night and 72o during the day along with high humidity will prolong bract color. Poinsettias suffer when over-watered. One should water only when the surface of the growing medium is dry to the touch. Since poinsettias to not like "wet feet", be mindful to discard water that might collect in a saucer place under the pot. If the pot containing the plant is foil-covered, be certain there is a drainage hole in the foil.

Saving a poinsettia and re-blooming it the following year is no easy task. If you are up to the challenge, then take good care of your plant throughout the course of the spring and summer, watering it and feeding it well. Next, the plant should be cut back severely (six to eight inches) around Labor Day; this will make for a more compact plant when it flowers. Since poinsettias in nature need 13 hours of uninterrupted darkness each day to flower, this regime must be carried out in the home if the plant is to flower. Setting your poinsettia in a dark closet every evening and removing it the following morning, starting in late September, is one way to accomplish this task. Once color development is well under way, this "long night" treatment can be discontinued.

Finally, contrary to the belief of some, poinsettias are not poisonous. Extensive testing conducted by The Ohio State University resulted in a clean bill of health for the poinsettia. So, enjoy your holidays by including a poinsettia as a part of your decor. You will be just one of millions of Americans who carry on this "new found" holiday tradition.

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REVISED: October 11, 2011