Euphorbia Euphorbia

This genus consists of over 2,000 species and is commonly called spurge. The plants can be annual or biennial, but most are perennial herbs, weeds, shrubs, and small trees. The genus is also known for many succulent species that resemble cacti.  All, however, emit a toxic milky latex when cut and have varying degrees of toxicity. The genus name, Euphorbia, is in honor of a Greek physician, Euphorbus, who used these plants for their medicinal properties in the 1st century A.D. It became the official botanical name for the genus in 1753 when published by Carolus Linnaeus. The common name, spurge, is derived from a French word, espurgier, which means "to purge." Many species' sap was once used as a purgative or laxative. 

While the preferred environment varies among species, most are best grown in full sun or bright indirect light and appreciate some afternoon shade. They should be grown in well-drained soil, preferably a cactus mix. Euphorbias are known for their drought tolerance, and many of the species store water in their thick, fleshy stems. For houseplants, it is best to allow the soil to dry out between waterings to prevent root rot. These plants prefer warm, dry conditions, and good air circulation. Many species thrive in USDA Plant Hardiness Zones 9 to 11 and need protection in colder climates, while others are more tolerant of the cold. Euphorbias can be propagated by seeds or stem cuttings.  

The cactus-like or succulent type of Euphorbias typically have thick, fleshy and angled stems with spines. Some species are fingerlike and multi-branched. Others are thorned, leafy, and have woody stems. This genus also includes the tropical plant commonly known as poinsettia that has bracts that are attached just below its small flowers. Euphorbias flowers are usually tiny, unisexual, and nondescript although in many species, the bracts around the individual flowers can be showy. Some species can grow quite tall; however, the typical plant attains a height of 18 inches and in the spring displays clusters of colorful bracts. These bracts should be trimmed off after blooming to maintain a tidy appearance. The fruits of this genus are capsules that usually split open when ripened and release their seeds.  In some areas, these plants can become weedy.  All species of spurge have a milky plant sap of low toxicity that can irritate skin or open wounds and can cause nausea or vomiting, if the plants are ingested. When attempting to propagate these plants or handling any part of these plants, be sure to wear protective gloves.

Many of the species of this genus are used as ornamentals. Some have medicinal value, some are weeds, and others can be invasive. They are diverse and range in size from small and compact to large and tree-like. They have unique flowers and many resemble cacti. 

Quick ID Hints:

• Symmetrical pairs of spines arising from a shield or old flowers (NOT areoles)
• Milky sap
• Flowers are a cyathium; one pistil or stamen and two colored bracts

Diseases, Insects, and Other Plant Problems: Monitor for aphids, mealybugs, spider mites, and scale. Potential diseases.include powdery mildew and root rot from overwatering. Sudden environmental changes such as temperature, light, or humidity can be detrimental to these plants.

Keep these plants out of the reach of children and pets due to its toxicity. Be aware of possible skin irritation from contact with its milky sap. Wear gloves for protection when handling these plants.

VIDEO Created by Laura Barth for "Houseplants, Succulents, and Cacti", a plant identification course offered in partnership with Longwood Gardens.