Poinsettia Care and Biology
In the wild poinsettia are larger and more gangly than what is marketed in North America. In a Florida garden they will be prone to leaf insects, particularly greenhouse whiteflies (Trialeurodes vaporariorum), which can then spread to other desirable plants in your garden.
Poinsettia leaves are green and red with the red-colored bracts often mistaken for flower petals because of their groupings and colors. Like many of our common plants in North America, poinsettia is largely an invention of the 20th Century, even though it was first introduced to the United States in 1829.
The poinsettia carries the common name of the person who introduced it to the U.S., the first ambassador to Mexico, Joel R. Poinsett (1779-1851). from Charleston, S.C. Poinsett was an important figure in American history prior to the Civil War, serving not only as ambassador, but also as senator for South Carolina and Secretary of War during the Van Buren administration.
18th century drawing of Crown of Thorns (Euphorbia milii var. splendens) and Poinsettia (Euphorbia plucherrima). Euphorbia is a genus of succulent plants belonging to the family Euphorbiaceae. It is the fourth largest genus of flowering plants. The name of the genus derives from Euphorbus, the Greek physician of King Juba II of Numidia, who married the daughter of Anthony and Cleopatra.
Poinsettia flowers are surrounded by colorful bracts (specialized leaves).
In botany, a bract is a modified or specialised leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are often (but not always) different from foliage leaves. They can occur smaller, larger, or of different colors, shapes and textures.
As Secretary of War between 1837 to 1841, Poinsett had the particularly racist and dishonorable distinction of commanding troops involved in decimating Native Americans in the South; Seminole Indians in Georgia and Florida and displacing the Cherokees who hadn't been slaughtered in the East to the Oklahoma Territory, though the xenophobic processes had begun a decade earlier. Arkansas' Poinsett County, established in 1838, is also named after Joel Poinsett.
To H. Marc Cathey, that was a challenge. As a horticulturist for the U.S. Department of Agriculture, part of Cathey’s job was to create plants that growers could sell—to help create markets for plants people didn’t even know they wanted to buy. While researching which chemical controls plant growth Cathey found a few compounds that would, first of all, keep the poinsettia small and bushy, a compact plant fit for a house instead of a tree fit for the wild. He also discovered a trick to hold the plants back from flowering: Every night, from 11 p.m. to 1 a.m., he would flash the plants with three seconds of light each minute, which would confuse them enough that they held their flower fire.
By the end of the decade, the plant had been fully transformed into the commercial product of today, and its popularity started to grow. By 1986, it edged out the chrysanthemum as America’s best-selling potted flowering plant (a spot it kept for decades, until edged out by orchids at the end of the 2000s). In the next decades, poinsettia would become $200 million industry, to the great triumph of the Ecke family. At one point, 90 percent of all poinsettias sold started life at the Ecke Ranch.
Paul Ecke III sold the Ecke Ranch in 2012 and the business is now owned by a Dutch company, Dümmen Orange. Dümmen Orange now offers poinsettia in some truly unusual colors like the bright pink "J'Adore," The orange "Fall Colors," and the white "Frozen" varieties. Read about the performance of some of these hybrids at Greenhouse Product News: Poinsettia Performance. My favorite of the new varieties is "Matinee Glitter," a deep red speckled with white-bracted plant.
The adoption of the common name "poinsettia" is due to a botanical tug-of-war that occurred between 19th Century botanists as they struggled to classify and name the plants that were coming to them from throughout the world. Robert Graham (1786-1845), a botanist in Edinburgh, Scotland, classified the plant as a new species and called it Poinsettia pulcherrima, with the new genus name honoring Poinsett and the species name translating from Latin as "very handsome" in reference to the flowers.
This name was accepted by our leading botanical figure of the time, Harvard’s Asa Gray, who was a friend of Graham. Meanwhile, in Berlin J.F. Klotzsch, the curator of the Royal Herbarium, was studying the collection of an earlier German botanist, Karl Willdenow (1765-1812), who had tentatively classified the plant as a member of the genus Euphorbia.
Eventually the botanists all agreed that Klotzsch was right, but by this time the name poinsettia had become entrenched as the common name for the flower.
After the Civil War, the poinsettia began to appear sporadically in East Coast greenhouses around the Christmas season. It was not until the turn of the century, when the Ecke family in California began growing poinsettias as a cut flower, that it really took off and became the floral symbol of Christmas. Today, the poinsettia is the largest single floricultural crop, with between 40 and 50 million pots sold each season.
Poinsettias (Euphorbia pulcherrima Willd. ex Klotzch) should be protected from cold, they are tropical natives of Mexico (and beyond) and won't respond positively to temperatures below 32° F. (0° C) nor to frost at temperatures above 32°.
Florida has lost most of its giant poinsettias due to development and imported pests like the devastating white fly. What remain are the virtually unnoticed Painted Leaf (Poinsettia cyathophora) that are found in the dense understory of remaining forests. Also called Fire on the Mountain or Wild Poinsettia these natives grow in protected locations across the South. They have the ability to extract water from the atmosphere and have thus survived despite persistent and debilitating drought that has killed off other native Florida species. This plant only grows to about 12-inches tall, so is easily overlooked but is a close cousin to the poinsettias found in garden centers around the world at Christmastime.