Bonsai Spurge

Popularly known as Bonsai Spurge, Euphorbia francoisii is a small, caudiciform succulent that has garnered the attention of collectors and succulent enthusiasts worldwide. Its rise in popularity is primarily attributed to Thai nurserymen, particularly Santiporn Sangchai, also known as Mr. Lek, who developed various cultivars of this plant. This species, belonging to the Euphorbiaceae family, boasts unique characteristics such as diverse leaf shapes, an ornamental caudex, and discreet yet elegant flowers.

Euphorbia francoisii is an endemic species of Madagascar, the fourth-largest island in the world, located off the southeastern coast of Africa. The plant evolved in an ecosystem that uniquely combines the biodiversity of tropical rainforests with the aridity of semi-desert areas, distinct features of the island. It primarily inhabits the southern and southeastern regions of Madagascar, including the provinces of Taolanaro and Andrahomana, at elevations of up to 50 meters (164 feet) above sea level. It thrives in well-drained soils with a high limestone content.

These areas are associated with xerophytic vegetation, consisting of plants adapted to survive under low water availability. Euphorbia francoisii is a classic example, with its thickened caudex and tuberous roots capable of storing water, enabling it to endure long periods of drought. However, due to habitat degradation caused by human activities, the species is threatened with extinction in its natural environment. Currently, it is almost exclusively found in private collections and botanical gardens.

The plant’s scientific name, Euphorbia francoisii, widely recognized, is actually considered a synonym for Euphorbia decaryi, first officially described by Jacques Désiré Leandri in 1946. The genus Euphorbia derives from the Ancient Greek name Euphorbus, a Greek physician who reportedly used plants of this genus for medicinal purposes during the reign of Juba II in ancient Mauretania, around 50 BCE. The genus Euphorbia is vast and diverse, ranging from small succulents to large shrubs, all characterized by a milky latex that can be toxic or irritating.

In popular culture and the ornamental plant trade, Euphorbia francoisii has earned the nickname Bonsai Spurge due to its resemblance to miniature trees. It is a small, decumbent or prostrate shrub with a tuberous, napiform root system that connects to the stem through a thickened caudex up to 3 cm (1.2 inches) in diameter. Its stems or branches are prominent, featuring spiral leaf scars. The stems may be angular or rounded, with stipular appendages that gradually develop into spiny structures.

The leaves are spirally arranged, ranging from succulent to leathery, and exhibit various shapes, including elliptical, lanceolate, and rhomboid. They have glossy surfaces with prominent veins, often displaying epidermal papillae that provide a rough texture and wavy margins. Leaf forms not only vary among individuals, varieties, and cultivars but also within the same specimen, changing shape and color depending on position or environmental conditions. This significant variation is due to the plant’s hexaploid nature, which offers many possibilities for selection. Inflorescences appear in late spring and summer, are terminal cyathia, pink or green in color, with bracts often larger than the flowers.

Euphorbia francoisii can be cultivated to create stunning miniature plant specimens. Despite its resilience and adaptability, maintaining this species requires careful attention to ensure its health and vitality, especially during its initial adaptation period. Its cultivation depends on a well-lit environment, suitable soil, and a precise watering routine.

This species demands plenty of sunlight, preferring full sun or, at minimum, light shade. Under direct sunlight, its leaves develop more vibrant colors and distinctive textures, while cultivation in shaded areas can result in etiolated growth, with thinner stems and elongated internodes. During winter, when the plant enters a state of semi-dormancy, it is essential to maintain good lighting to avoid compromising its health.

The ideal soil for Euphorbia francoisii must be well-draining, consisting primarily of inorganic materials such as pumice, gravel, and expanded clay, with a small amount of organic matter like peat or coconut chips. This formulation prevents moisture accumulation around the caudex and roots, reducing the risk of rot.

During summer, the plant requires regular, abundant watering with perfect drainage. The rule is simple: water deeply only when the substrate is completely dry. In winter, watering intervals should be extended or even suspended to prevent excessive moisture, as Euphorbia francoisii is particularly susceptible to rot when kept cold and damp outside its active growth season.

In summer, use a fertilizer specifically formulated for cacti and succulents, rich in potassium and micronutrients. Apply it monthly or as directed by the product’s instructions. This practice is even more critical for plants grown in very poor soils or containers, as it helps sustain the development of new leaves and the health of the caudex. Avoid organic fertilizers such as worm castings or oilseed cakes, as these may decompose and impair the substrate’s drainage.

To expose the caudex and tuberous roots of the Euphorbia bonsai, showcasing their sculptural qualities, it is necessary to raise the caudex during the plant’s repotting. Ensure this operation is performed on well-adapted plants with significant growth. Small seedlings may not survive. Begin by carefully unearthing the plant, washing its roots, and removing fine roots that compromise the aesthetic of the portion that will remain above the substrate. Then, replant as usual, keeping the sculptural part elevated. Whether or not you choose to raise the caudex, replace the substrate every two years during repotting. Use this occasion to remove dead branches.

The Euphorbia francoisii can be propagated by both seeds and cuttings. Each method has its particularities and challenges, with cuttings being the most common due to the difficulty of obtaining and germinating viable seeds. Propagation by cuttings should ideally be performed in spring, when environmental conditions are more favorable. To carry out the procedure, cut a healthy segment just below a leaf node, always using clean tools to prevent fungal or bacterial contamination.

Allow the cutting to dry for a few days in a protected location, enabling the wound to heal completely—failure to do so may result in the cutting rotting before it can root. After the healing period, partially insert the stem’s tip into a well-draining substrate and maintain a slightly moist environment, but never waterlogged. Roots typically develop in about two weeks, at which point the new plant can be transferred to a permanent location with optimal growth conditions.

Propagation by seeds, though less common due to the time required for the plant to mature, is crucial for those interested in hybridization and genetic selection. Additionally, the perfect development of the caudex and a less branched appearance are achieved only through seed planting. Euphorbia francoisii seeds quickly lose viability after harvest, so they must be planted immediately. During germination, the soil should remain moist but never saturated. Although germination occurs within one or two weeks, the plant’s development is slow, taking years to reach maturity and develop the characteristic caudex.