Poinsettia

The poinsettia (Euphorbia pulcherrima) is a flowering plant from the spurge family that’s big business in the floral trade. Native to Mexico and Central America, it’s famous for its red and green leaves and is a staple of Christmas decorations. Its English name comes from Joel Roberts Poinsett, the first U.S. minister to Mexico, who brought it to the United States in the 1820s. Lately, some have pushed to call it by its Nahuatl name, “cuetlaxōchitl,” because of Poinsett’s involvement in slavery and the Trail of Tears. Poinsettias are shrubs or small trees that can grow from 0.6 to 4 meters tall. Despite a common myth, they aren’t dangerous to pets or children—eating them usually causes no harm, though it might lead to nausea, vomiting, or diarrhea.

Wild poinsettias grow from Mexico to southern Guatemala, mainly on mid-elevation slopes facing the Pacific. One inland population in Guerrero, Mexico, is thought to be the ancestor of most cultivated ones. Their habitat is fragmented due to heavy deforestation. The Aztecs grew them for traditional medicine. They later became tied to Christmas and are now popular seasonal decorations. In the U.S., about 70 million poinsettias are sold over six weeks each year, many from Paul Ecke Ranch, which supplies half the global market and 70 percent of the U.S. market.

The plant was first described as a new species in 1834 by German scientist Johann Friedrich Klotzsch, who credited Carl Ludwig Willdenow with the name “pulcherrima.” The holotype came from an 1803–1804 expedition by Alexander von Humboldt and Aimé Bonpland in Mexico. The common name “poinsettia” was in use by 1836, after Poinsett, a botanist and diplomat who likely started sending plants from Mexico to his South Carolina greenhouses as early as 1826. Before that, it was called “Mexican flame flower” or “painted leaf.” In Turkey, it’s known as “Atatürk çiçeği” (“Atatürk flower”), a name that came from a false newspaper report claiming a professor suggested it after seeing Mustafa Kemal Atatürk visit a college in Kayseri.

Euphorbia pulcherrima is a shrub or small tree, usually 0.6 to 4 meters tall, with dark green, toothed leaves 6 to 16 centimeters long. The bright red bracts—often mistaken for petals—are actually leaves. Cultivars come in orange, pale green, cream, pink, white, or marbled. Their color comes from photoperiodism: they need at least 14 hours of darkness for 6 to 8 weeks straight to change color, plus plenty of light during the day. Semi-evergreen, they drop most leaves in winter. The real flowers are small and unassuming, grouped in cyathia (yellow structures at the center of each leaf cluster). Pollination in the wild is unknown, though wasps sometimes visit the cyathia. All Euphorbiaceae flowers are unisexual and tiny; in Euphorbia, they’re reduced further and clustered. Extrafloral nectaries were first noted in 1932.

The idea that poinsettias are toxic is a myth, spread by a 1919 urban legend about a child dying after eating a leaf. In 1944, H. R. Arnold’s book *Poisonous Plants of Hawaii* included it based on that hearsay, and Arnold later admitted it wasn’t proven. In 1970, the FDA wrongly stated that one leaf could kill a child, and in 1980, a North Carolina county banned them from nursing homes. Tests on rats failed to find a poisonous dose, even at levels equal to eating 500 leaves or nearly 1 kg of sap. Contact with the plant usually has no effect on children or pets, though swallowing it might cause nausea, diarrhea, or vomiting. Skin contact can cause a rash. A review of over 20,000 calls to poison control centers from 1985 to 1992 found no deaths; 92.4% of cases had no effect, and 3.4% had minor effects. For cats and dogs, ingestion rarely needs treatment—maybe mild drooling, vomiting, or diarrhea. Eye exposure can cause irritation, and sap may cause itchiness, redness, or swelling. It can also trigger asthma and allergic rhinitis in some people.