Caper spurge (Euphorbia lathyris) is most commonly known as an invasive weed. It is considered toxic to humans and almost all species of livestock. The exception to this is that some goats can eat caper spurge without becoming ill. However, the plant’s toxins will be carried into the goat’s milk, making it unfit for human consumption. The toxicity has been put to use, however, in deterring moles and gophers from invading gardens.
I. Appearance and Characteristics
Euphorbia lathyris, the caper spurge or paper spurge, is a species of spurge native to southern Europe (Italy, Greece, Spain, Portugal), northwest Africa, and eastward through southwest Asia to western China.
Other names occasionally used include gopher spurge, gopher plant or mole plant.
It is an erect biennial (occasionally annual) plant growing up to 1.5 m tall, with a glaucous blue-green stem. The leaves are arranged in decussate opposite pairs, and are lanceolate, 5–15 cm long and 1-2.5 cm broad, glaucous blue-green with a waxy texture and pale greenish-white midrib and veins. The flowers are green to yellow-green, 4 mm diameter, with no petals. The seeds are green ripening to brown or gray, produced in globular clusters 13–17 mm diameter of three seeds compressed together.
All parts of the plant, including the seeds and roots, are poisonous. Handling may cause skin irritation as the plant produces latex. While poisonous to humans and most livestock, goats sometimes eat it and are immune to the toxin. However, the toxin can be passed through the goat’s milk.
Away from its native range, it is widely naturalized in many regions, where it is often considered an invasive weed. It grows in partial shade to full sun in USDA zones 5–9.
II. How to Grow and Care
Sunlight
Spurges naturally grow in places that have plenty of sunlight, but some species can tolerate partial shade. Full sun provides the best environment for spurges. If they are grown indoors, spurges need at least 6-8 hours of direct sunlight every day for proper development.
Watering
Caper spurge needs regular watering about once a week, especially during growing seasons. The plants don’t need great amounts of water during temperate environmental conditions, but during hot summer days they need as much water as any other plant. Caper spurge needs to be watered when the planting medium is dry for 5 cm at the surface. Those grown in indoor environments also need a sufficient amount of moisture during the resting season. To avoid excess moisture in the medium, it is best if small amounts of water are added from below.
Soil
Spurges aren’t picky when it comes to soil type. They can grow in a variety of soils. Some species of Euphorbia can even thrive in nutrient-poor soils, requiring only that the soil be well drained. If the soil is full of moisture and is prone to water retention, it will most likely cause root rot.
Fertilizing
Caper spurge doesn’t require large amounts of fertilizer for normal growth and development. In fact, very little fertilizer is required. As mentioned earlier, some species can thrive even in very poor soils, as long as those soils are well drained. Fertilizer should only be applied when the plants start showing nutrient deficiency symptoms on lower leaves. When the lower leaves turn yellow, it is time to add half-strength liquid fertilizer to the soil. That will keep the plant well fed for several months.
Planting Instructions
Dig a hole twice as wide as the plant’s root ball before planting. Then, turn the container with caper spurge upside down and let the plant slowly fall into your hands. Place the plant upright in the hole and slowly fill in around the roots with loose and fertile potting mixture, adjusting the planting depth until it is just right. Water it once. Do not overwater, as standing water is not good for the plant.
Pruning
In early spring, if there are any damaged stems, they need to be removed to keep the plants healthy and to optimize their nutrient management. It is advised to cut back a certain number of stems after blooming in order to stimulate consistent flowering and growth of new foliage. When cutting a stem, cut at the stem’s base. It is very important to use gloves while handling and pruning caper spurge, because their tissues contain milky-white latex sap which is poisonous and can irritate the skin.
Propagation
Caper spurge can be successfully grown from seeds, but the seeds are rarely commercially available because they are difficult to germinate and stay viable only for a short period of time. Caper spurge is most commonly propagated via cuttings.
It is important to wear gloves while working with caper spurge cuttings and to clean the pruning shears thoroughly after pruning, so that any unwanted contact with the sap is avoided. Before planting, it is necessary to leave the cuttings to dry for 2-3 days. This will prevent rot from developing and enable proper formation of the callus tissue. It is advised to plant the cuttings in a soilless medium, such as peat moss, because it provides an optimal environment for proper root development.
Cuttings should be misted regularly, and the pots in which they are planted need to be wrapped in either foil or a plastic bag to preserve moisture. The bag or foil needs to be removed for two hours each day to provide sufficient air and to prevent excess moisture in the medium. If this step is skipped, molds and rots can easily develop and damage the health of the young, sensitive cuttings. When the cuttings develop a root system, they are ready to be transplanted into soil.
III. Uses and Benefits
- Garden uses
Caper spurge is helpful as a garden plant because the roots are toxic and aversive to moles, discouraging these pests from damaging flowers and vegetable plants. You can also plant it in home orchards for the same purpose.
- Medicinal uses
Despite its toxicity, various parts of the mole spurge plant have been used medicinally through the years. The seeds were used by French peasants as a purgative, similar to castor oil. Folklore about mole plants says the latex has been used for cancers and warts. Further information about mole plants says it is a Mediterranean native, brought to the United States for the use of repelling rodents in orchards and various other agricultural locations.
IV. Harvesting and Storage
When harvesting cuttings, remember to wear gloves, as the sap can be irritating to the skin. It can be cut from the base of the stem. Soak the end of the cutting in hot water for 10 seconds to stop the milky sap from oozing. The vase life for the cutting will be about 5-7 days, and some flower food can extend its life.
When the fruits of Euphorbia plants are ripe, they burst and scatter the seeds over a large surface area. In order to harvest all the seeds, the individual fruits or the entire plant must be wrapped in nylon, gauze, or similar material before the ripe fruit bursts and releases the seeds.
