Euphorbia, an Enigmatic Group of Plants

Euphorbia (You-FOR-bee-ah) is a huge genus of Diverse and dramatic flowering plants with 2,000 species. Some are tiny annuals, others form huge trees, with every size in between well represented. Most are succulent, though some, like the poinsettia, are not. Euphorbia varieties are found all over the world, with concentrations in the temperate regions of Africa and the Americas. This is a strange and enigmatic group of plants, often confused with cacti, for the many prominent thorns many euphorbias produce. Always treat this plant with respect. In addition to many producing thorns, all euphorbia are toxic and produce a milky white, latex sap that can be very irritating or downright caustic to some people. So-is a plant this peril really worth growing? Let’s see why many gardeners answer a resounding Yes!

All About Growing Euphorbia

Euphorbia Cactus Conundrum



The wicked sharp thorns of the Euphorbia milii above clearly demonstrate why so many confused euphorbias with cactus. While they are botanically distinct, the similar traits of euphorbia and cactus resulted from millennia of adaptations to similarly harsh environments. This is known as convergent evolution. Both succulent euphorbia and cactus store water in their stems to support the plants in times of drought. Both developed long, sharp spikes to protect their water stores from foraging animals and to protect the plant against blazing heat. The spikes produce a small bit of shade, while breaking up the airflow around the plant, limiting moisture loss to the wind.

The differences between Euphorbia and Cactus

Although all cactus are succulents, not all succulents are cactus. Most euphorbias are succulent. Many of them look like cacti, and are typically referred to as “euphorbia cactus”, but no euphorbia is biologically a true cactus. Confused yet? Cactus all share defining characteristic areoles. This is a highly modified branch that appears as a small, round bump, that supports blooms, spines and film. Even spineless cactus all have areoles, but no euphorbia does. However, many euphorbia cactus do have thorns growing from round bumps. These bumps do not produce blooms or film and are not considered areoles.

Cactus spikes are spines, which are modified leaves. They are typically quite narrow, and needle-like, looking as if they were pushed through the skin of the cactus from the other side. Cactus spines always develop from areoles. The spikes on euphorbia are thorns, which are modified stems or branches. They are typically much wider at the base and look as if the skin of the plant is pulled to grow into a thorn. While some euphorbia thorns appear on bumps, many do not. I confess, I am not great at telling the difference between euphorbia bumps and cactus areoles.

Thus, have clearer distinctions between euphorbias and cacti. When in bloom, they are easy to tell apart. The flowers of cacti are complex and typically large and quite flamboyant. The flowers of euphorbia are quite small and simple, with only female or only male parts to each flower. Typically, the colored “petals” of euphorbia flowers are actually bracts, or modified leaves, and not true flowers. More on euphorbia flowers below. The final distinction between the two groups is their sap. Cactus sap is usually quite clear, while euphorbia sap is characteristically milky white and quite toxic. More on this to follow.

When you cut any euphorbia variety, it will bleed copious amounts of milky white latex sap. Many common names for euphorbia varieties, like African milk tree or milk bush, refer to the white sap. This sap can be highly irritating to many people, causing severe skin rashes. A tiny brush with your eyes, nose or mouth will be terrible painful even for those not sensitive to it on their skin. Take great care with this sap. Your skin can take as much as an hour to react even if you are very sensitive to it. And if you get sap on your shirt, and then after pull it off over your head, you risk getting sap in your eyes. Don’t take that risk!

Euphorbia sap is toxic. It was developed as a defense against animals desperate to feed on the moisture stored within the stems of the plant. Sap also has antibacterial and antifungal properties that quickly heal any plant wounds. When you take euphorbia cuts, there is no need to wait a few days for the healing Cut. The sap ensures the cutting remains healthy while it begins to root.

The fierce thorns and toxic sap make euphorbia a plant that must be treated with respect. Take care of the pruning of this plant, and keep it out of the reach of the plant-eat animals or small children. But there is no need to fear this plant. Many, many garden plants are as toxic or more so than euphorbia. Be considerate and take precautions. And you may well appreciate how highly resistant all euphorbia varieties are to deer, rabbits, squirrels and gophers, thanks to those thorns and sap.

Euphorbias are All About Texture!

A primary allure to growing succulent euphorbias is their fabulous texture! Here, Euphorbia tirucalli ‘Sticks on Fire’ looks like a sea coral adding glorious stress coloring and airy, whimsical texture to the garden. In your garden or mixed arrangements lend drama and excitement with their unusual forms. Euphorbia cactus thorns add an edgy vibe to mixed rosettes and other smooth succulents.

Euphorbia Flowers

Much of what we see in the showy and long-lasting blooms of euphorbia varieties are not truly flowers. These are colorful bracts or modified leaves that surround the tiny, highly minimalized euphorbia flowers. Each flower is male or female, with only the essential parts required for sexual reproduction. The flowers have no true petals or sepals or nectar to attract pollinators. The male flowers have a stamen, and female flowers have the pistil-and that is it. Although euphorbia does produce nectar to appeal to bees, it is produced and bourne outside the true flowers.

These unusual bloom structures lead to an extended flush of the colorful bracts most people look for in blooming plants. In fact, the Euphorbia milli showed above, and commonly called the Crown of Thorns plant, flowers nearly year round!

Getting sun exposure right is still important for succulents, but euphorbia are less likely to stretch out in less ideal light. In the morning sun with protection during the heat of the day, to avoid sunburn. If you are looking for signs of stress, then slowly, increase the sun exposure until both your plant and you are satisfied with its location.

Leave a Reply

Your email address will not be published.