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The Poinsettia and its Relatives

Updated December 18, 2018

David Graper

Professor Emeritus of Horticulture Science

The Holidays are a great time to get together with friends and family, exchange gifts, enjoy a good meal together and in many cases admire the beauty of the classic holiday plant the poinsettia. Did you know that of all of the different kinds of potted plants that are sold in this country that the poinsettia is number 1? I find that pretty interesting considering it is really only for sale for a few weeks out of the year, leading up to Christmas. And, I think you can guess how much any leftover plants on the florists’ or big box’s store shelves are worth the week after Christmas. Not much more than colorful compost material, which is where I think most poinsettias should end up by the first of March or so. I too often see half-dead, scraggily plants still surviving in someone’s office or on display in their homes. Often the owners of these plants are quite proud of the fact that their poinsettia is still alive. They then usually ask me what to do with it when it is done blooming. I tell them to toss it in the compost pile but that is usually not the answer they were looking for.

You might gather that poinsettias are not my favorite plants. While it is true that the typical red poinsettia is not my favorite, I do enjoy some of the other cultivars of poinsettias that have bracts ranging in color from creamy white or yellow to pinks and lavender to speckled and striped and more. Plant breeders went to a lot of trouble to develop those good old red poinsettias that could be reliably grown and brought into bloom for Christmas. The ancestors of the modern poinsettia were much more challenging to grow and maintain in the home. The purchaser was lucky if they made it to New Year’s Eve. They are still a challenging plant to grow well. The problem now is that you can forget to water them for a week or more, or let them sit in water in a saucer and see most of the leave turn brown and fall off but they will often still survive. Getting them to rebloom, and to do it in time for Christmas is not easy for the typical home gardener. (I will provide more information on that next week.) So I feel that the best thing to do is enjoy it for a few weeks, then get rid of it and move on to a fresh new plant and just buy a new poinsettia next December.

Despite the fact that poinsettias are not my favorite plant, some relatives of poinsettia (Euphorbia pulcherrima) are excellent additions as houseplants on your windowsill while some of the hardier ones make great perennials too. They all share some common characteristics like a milky sap in the stems and leaves, and strange looking flowers called cyathia. The red color on poinsettias comes from colored leaves, called bracts, which change color when the day lengths get short in the fall of the year. The true flowers are little round structures in the center of the bracts. They look similar in some of the other plants that I will describe later.

Baseball Plant (Euphoria obesa)

A round, baseball-shaped plant with a cluster of white flowers at the top.
Euphoria obesa, the “baseball plant”.

Probably my favorite poinsettia relative is called the baseball plant or Euphorbia obesa. Once you see the plant I think you will understand the species name of “obesa” because that is how it looks, mostly round, like a baseball. The main color of the plant is blue-green but it develops little patches of striations that make the plant almost look like it is quilted. It only flowers occasionally and the flowers are easy to miss. The plant is also interesting in that it generally does not grow any leaves, at least not like we usually think of leaves. It is fun plant, slow growing and needs to be grown in a full sun location.

Crown of Thorns Plant (Euphoria milii)

A potted plant with branching pink flowers.
Euphoria milii, the “crown of thorns plant”

Another indoor plant that is fairly popular is the crown-of-thorns or Euphorbia milii. This plant is aptly named since the stems are covered in spines nearly an inch long. It can often be found for sale in the spring for Easter, but it can be a long-lived plant. This Euphorbia does usually have leaves, at least on the top inch or two of the stems. The actual flowers are much showier than on most Euphorbias. They are usually about ½” in diameter, often form in clusters on stems about 2” long and range in color from creamy white to red and pink.

Euphoria Horrida

A cactus-like plant with green and white growths and brown spines.
Euphoria horrida looks like a little cactus.

There are lots of other types of Euphorbias that can be grown as houseplants here or as outdoor plants in warmer climates. Most of these are types of succulents that can withstand periods of drought or go without watering in your home for weeks at a time. One more that I want to mention is Euphorbia horrida. This plant looks like a little cactus with many roundish plants that usually grow around a larger central plant. The plants are ribbed and usually have short, spine-like projections along those ribs. Minute leaves and flowers might be seen occasionally as well at the ends of these “spines” or closer to the ribs of the plant itself. It is also a fairly slow growing plant that will be comfortable in a 6” pot for many years.

Euphoria Polychrome

a sprawling bed of bright yellow flowers
Euphoria polychrome can be great in a garden

Some Euphorbias can be great plants in the garden too. Probably my favorite there is Euphorbia polychroma or cushion spurge. This is a green, bushy plant that emerges fairly early in the spring. It grows to nearly a foot tall and round with medium green foliage. Then, about the end of April or early May, it starts to flower and the upper leaves turn bright yellow, sort of like the poinsettia’s upper leaves turning red. It puts on a quite a show for several weeks but then the yellow color fades out. Like the poinsettia, the true flowers are not showy at all; they don’t even have petals or sepals. It still manages to produce seed though, so it can spread around in your garden a bit.

There are a few other species of Euphorbias that are hardy enough to grow here in this region. Most are grown for their interesting and colorful foliage. There is a fairly new “plant on the block” called Euphorbia graminea or hypericifolia, sometimes sold as ‘Diamond Frost’, ‘Angel Frost’ or a similar name. It is usually sold as a bedding plant in the spring. It works well in containers or in the ground, it tolerates drought, grows best in full sun and produces loads of tiny white flowers all summer long. It has grown well here at McCrory Gardens but seems to grow better in a container with more well-drained soils than we have in most of our gardens.

If you do a search for Euphorbia on the internet you will find dozens of other plants to try. I must ad d a word of caution however. The milky sap that most of these plants have can cause dermatitis on the skin of sensitive individuals. The sap of some of the succulent type species of Euphorbia can cause a severe reaction in many people. People need to wear gloves when working with the plants, and probably goggles too! I will never forget the time I tried taking cuttings of a Euphorbia trigona I had. When I tried cutting off a stem, it squirted some sap into my eye. My eye felt like it was on fire. I ended up throwing away my contacts because I could not clean it off of them again. I later heard from an Optometrist friend of mine that one of his patients suffered a melted cornea thanks to the sap of a similar plant. Needless to say, I soon got rid of that plant. So, enjoy the Euphorbias but respect them too.

Related Topics

Flower, Plant