The Garden Guru: All about poinsettias

12/06/2013 12:00 AM

12/05/2013 11:16 AM

You’re probably thinking, “Another story about poinsettias? Another time that I’ll have to read that the first American minister to Mexico, Joel Roberts Poinsett, fell in love with this plant and brought it back to his native home in South Carolina? Oh, please!”

Well, frankly, I’m kinda tired of those old stories, too, so I thought I’d ramp things up just a bit. I’ve assembled some fun facts that you probably didn’t know. It’s an amazing plant whose past and present are filled with myths and mystique.

First fact: All poinsettia flowers are the same color. Can you name it? I’ll use that as a tease into the other topics, but we’ll reveal the answer just a little bit farther down in the story.

Myth-buster fact: Poinsettias are not poisonous! The research that proved that was done at Ohio State University in 1975, but almost 40 years later, the rumor still makes the rounds. The latex sap that drips when a poinsettia stem is broken or cut can certainly be irritating to our eyes and our skin, but we’re not going to die because we come into contact with it. There are plenty of common, everyday plants that actually are poisonous, but poinsettias are not among them.

Poinsettias grow fast. As my grandson Joseph would say, “super-fast.” The lovely big plant that you’re about to buy was a small, unrooted cutting in early August. Greenhouse growers love them because they’re quick from start to finish, and because they’re highly salable in a short period of time. They’re not without challenges, but they’re good cash crops for the end of the growers’ year.

I’m often asked about reflowering a poinsettia the following Christmas, and to keep our promise not to cover old ground here today, I’m just going to encourage you not to try it. This year’s plant, left to grow on its own, would be 10 feet tall by next Christmas. And it wouldn’t tolerate frost, so you’d have to bring it indoors. It’s not worth the struggle.

Poinsettias bloom around Thanksgiving because they’re photoperiodic. That’s the plant physiologist’s term that says that they measure the length of the dark period (night) to determine when to come into bloom. When nights reach 14 hours long, the plant turns from vegetative to reproductive. There is a flowering hormone produced in the growing tips of the stems. It is destroyed by light, so if you want to prevent poinsettias from flowering, you simply have to turn on a light for a minute or two in the middle of the night.

One of my fellow OSU grad students had a major part of his research ruined because the night watchman came in each night and turned the lights on just long enough to check the greenhouse thermostats.

As the plants grow taller, their leaves begin to take on the characteristic colors of red, pink or creamy white (among others). But those are modified leaves known collectively as bracts. The real flowers are the small, round, yellow structures in the centers of the bracts. So, the true answer is that all poinsettia flowers are yellow.

There are some interesting side notes on Joel Roberts Poinsett himself. Most plants are named for the botanists/taxonomists who found and first identified them. We know little or nothing about the botanist otherwise. Poinsett, however, was a career politician, first a member of the South Carolina legislature, then the United States House of Representatives.

In 1825 he began a four-year service as U.S. minister to Mexico, returning to become U.S. Secretary of War. He was a co-founder of the National Institute for the Promotion of Science and the Useful Arts (an early building block of the Smithsonian Institution). All of that from the man whose name would forever be tied to a plant he had admired during his time in Mexico and then introduced to his native home in South Carolina in 1825.

Jump ahead by 75 years, and meet Albert Ecke, patriarch of one of the most recognized families in American horticulture. He took interest in the plant and began cultivating it. His grandson Paul Ecke Jr. was responsible for poinsettias becoming recognized as the iconic Christmas flower. That was the 1930s, and the varieties that were being grown had Ecke family names given to them.

On a personal note, while I was at Paul Ecke Jr.’s alma mater, Ohio State University, working on my degrees in the 1960s, my fellow graduate students were doing their research on new poinsettia varieties, growth retardants to keep the plants shorter and means of producing more uniform plants more efficiently.

During my years there, I had the opportunity to meet Mr. Ecke, but it was years later before I realized the full impact of his work. Even today, the Ecke family supplies 70 percent of the cuttings and small starter plants used in the American greenhouse trade, and better than half of the poinsettias worldwide. What a legacy family!

Our final little-known fact about poinsettias actually comes from their botanical lineage. They are in the massive and curious Euphorbiaceae plant family. Some of their close cousins include copper plants, crotons, crown of thorns, pencil plant, tapioca and the native Texas late-summer wildflower snow-on-the-mountain.

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