Poinsettias: A Christmas Horticulture Lesson

December is a strange time to be thinking of flowers, but poinsettias in shades of red, pink, and white (and now almost any color you can think of) are ubiquitous at this time of year. This tradition linking poinsettias to Christmas dates back to a legend from 16th century Mexico. It is said that a little girl was too poor to bring a Christmas gift for Jesus' birthday. Instead she picked a bouquet of weeds and brought them to the church altar, and they turned into beautiful red poinsettias. The plants also have symbolic value in the Christian religion on top of the legend. In the Christmas story, the star-like flower shape represents the Star of Bethlehem that led wise men to baby Jesus.

Poinsettias (scientific name Euphorbia pulcherrima) are native to Mexico. They are a member of the spurge family, botanically known as Euphobiaceae. We usually see them as small shrubby plants around the holidays, in Mexico they grow as small trees and can reach up to twelve feet tall. Other members of this diverse family include the croton (a popular tropical house plant), rubber tree, cassava (an important food crop in South America), and castor oil plant. All members of the family have a milky latex sap and unique flower clusters called cyathia. Plants from the spurge family are used in medicine, industry, agriculture, and as ornamental plants.

One of the most interesting facts about poinsettias is that the colorful parts of the plant are not petals - they are modified leaves called bracts. Place a colored bract right next to a green leaf, and you'll see that they are identical except in color. In order for the bracts to turn from green to their more festive colors, poinsettias need long nights and specific temperatures. Commercial growers control the temperature and use light-blocking fabrics to force coloration to meet timelines for sellers. Poinsettia bracts are normally somewhere in the red to white spectrum. Pale green, yellow, reddish purple, and orange-ish pinks can also be produced through hybridization and other breeding techniques. Any other colors you see, such as blue or orange, are from dye or paint (of course, any glitter you see is also added artificially). Keep reading for some more interesting cultural and botanical facts about poinsettias.

  • The Aztecs used poinsettias as a red dye, a fever medicine, and in religious rites where red symbolized purity.
  • There are well over 100 varieties of poinsettia, and each has its own name. Some are quite imaginative! My favorites include 'Freedom Salmon', 'Sparkling Punch', and 'Jingle Bell Rock'
  • We get the common name of poinsettia from Joel Roberts Poinsett. He was the first American ambassador to Mexico, and he brought the poinsettia to America in 1825.
  • The branching, many-flowered shape we are familiar with in poinsettias is actually the result of a pathogen. It encourages more branching and flowering, but otherwise the plants are fine.
  • The retail market of poinsettias in the U.S. is worth $250 million each year, making poinsettias the best-selling potted plant in North America.
  • For a long-lasting poinsettia, check the true flowers in the cyathia at the center of the bracts. If the flowers are still green or reddish and closed, your plant will last longer. If the flowers are already open to reveal yellow pollen, the poinsettia is farther along in its bloom cycle and won't last as long.
  • The sap from poinsettias can cause skin irritation and mild stomach discomfort, but they don't pose a serious health risk to people or pets.

Want to learn more about this fascinating plant? The University of Illinois has a great website called The Poinsettia Pages with all kinds of fun facts, including more tips on how to pick the best plant.


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