5 fun facts you may not know about poinsettias — and a few myths busted | St. Louis Public Radio

5 fun facts you may not know about poinsettias — and a few myths busted

Dec 31, 2015

Poinsettias are sold by the millions every year, almost all of them between Thanksgiving and Christmas. As popular as these holiday flowers are, there still may be a few things about them that could surprise you. Here are five fun facts about poinsettias we wanted to share.

1. Poinsettias are named after that dog, the pointer

Uh, no. The poinsettia — pronounced "poyn-SET-ee-ah" or "poyn-SET-ah" — is named for Joel Roberts Poinsett, an American statesman, physician and amateur botanist. He saw the shrub with its brightly-colored red leaves in Mexico, while serving as the first U.S. Ambassador to that country in the late 1820s. He brought the plant back to his home state of South Carolina, and it was later named "poinsettia" in his honor.

The true flowers of the poinsettia are small and yellow. They are surrounded by much larger, colorful modified leaves called bracts. Here the bracts are bright red, although they can be other colors like pink or white.
Credit fine_plan | Flickr Creative Commons

2. Poinsettias have always been small houseplants

Wrong again. In Mexico, the poinsettia (Euphorbia pulcherrima) is a perennial shrub that can grow up 12 feet high. Here, commercial growers have bred dwarf varieties that can thrive as potted plants. Today, the poinsettia is the highest selling potted flowering plant in U.S.

3. The flowers give them that pretty red color

Well, in a way. The bright red parts of poinsettias that may look like flowers are actually modified leaves, called bracts. The bracts turn from green to red during flowering, but the plant's true flowers are tiny yellow buds clustered in the center of the bracts.

4. Poinsettias are poisonous

Not true — although that urban legend persists. Based on studies with rats in the lab, eating a poinsettia's leaves will not kill you (or an unwelcome holiday visitor). Still, it's probably not a good idea to use them in a salad, unless you want to spend the holidays in the bathroom, dealing with an upset stomach, vomiting or diarrhea. And some people can have an allergic reaction if the poinsettia's sticky white sap gets on their skin. To be on the safe side, it's best to keep all plants away from children and pets.

5. Poinsettias wither and die once the holidays are over

A poinsettia bract turns from green to red.
Credit Debbie Johnson | MU Extension Communications

Actually, poinsettias can live for years if you take care of them. And if you want a real challenge, you can even get them to bloom and turn red again next Christmastime. University of Missouri-Columbia plant scientist David Trinklein recommends the following steps:

  • During the winter, keep your poinsettia in bright but indirect light, being careful not to over-water it or leave its pot standing in a saucer of water.
  • Once the danger of frost is past, put the plant outdoors and fertilize it on a regular basis.
  • Around Labor Day, cut back (or "pinch") the summer growth. The poinsettia will respond by sending out new branches, giving you a shorter, fuller plant.
  • In late September — Trinklein suggests the 25th — make sure the poinsettia is in total darkness overnight, by putting it in a closet, or covering it with a light-proof hood, for example. Just don't forget to take it out again in the morning, warns Trinklein. "I’ve had people call me and [say], 'Well, I put my poinsettia in a closet last September. Is it time to take it out now?' Sorry, but it of course undoubtedly was dead, because [a] poinsettia is a green living plant that needs sunlight," Trinklein said. "The thing of it is, it also needs a long, uninterrupted period of darkness in order to flower."

Once buds appear and the bracts start turning from green to red, you can stop the dark-light routine and put your poinsettia back on display.

Trinklein admits that after all that work, the results can be disappointing: you probably won't get back the same vivid color the poinsettia had when you first bought it. "But nonetheless," Trinklein said, "people can still feel that sense of satisfaction that 'hey, I took this poinsettia through the summer, and I got it to re-bloom again,' which in the home is not an easy task."

Follow Véronique LaCapra on Twitter: @KWMUScience