Euphorbia neorubella

Euphorbia neorubella

Family: Euphorbiaceae
Common Name: red monadenium, red monadenium bonsai tree
Synonyms: Monadenium rubellum, Monadenium montanum var. rubellum
Origin: Euphorbia neorubella is native to Kenya, being found in dry rocky slopes at elevations of 4,000-5000 feet (1,2).
Description: Euphorbia neorubella is a perennial succulent herb with a caudiciform trunk base, comprised of either a singular or cluster of tubers in a twisting formation, each up to 6 inches long (1,2,3). In habitat, younger plants will have a concealed caudex, as they age the tubers swell, they begin to be exposed above the soil surface, usually after 5 years of growth (2,7). This plant usually supports 1-3 stems from each caudex, increasing stem yield with age (1,2). Each stem can grow up to 12 inches long, initially with an upright formation until increasing elongation causes a decumbent growing habit (1,2,3,7). The stems have a ridged texture, with longitudinal purple and green striping (1,3). Its leaves are narrow and pointed with a smooth leaf margin, and its lamina has an overall purplish-green, sometimes red, streaking pattern with a deep purple underside (1,3,7). The leaves can have a reddish hue when the plant is growing in intense light (2). At each leaf axil there is dentate stipules with a sheath-like appearance (1,7). The tubular flowers can range from a pink to purple coloration and are usually 1.5 cm long, forming on a cyathium (1,3,4). The fruit is a 3-lobed capsule approximately 5mm long, with a truncated form where it meets the pedicle (1). The seeds are small and oblong, also with a truncated base, and are a light brown coloration (1).

Interesting Features:
- Along with all plants in the Euphorbia genus, Euphorbia neorubella has a unique structure of aggregated flower clusters called a cyathium, which is found nowhere else in the plant kingdom (3,4).

Uses: Red monadenium is lauded for its unusual appearance, and near year-round blooming, as well as being sought after by bonsai enthusiasts for its attractive caudex (1,2). This plants sole ethnobotanical use is as an ornamental, as a unique accent piece. Although beautiful, this plant is toxic and its sap can cause irritation to the skin and eyes, so care should be taken to keep out of the reach of children and pets (2,3,4,5).

Cultivation and Care:

Watering: This plant is drought tolerant but requires regular watering during the growing season (spring-fall), especially when flowering (2,3,5,6).
- This plant can go dormant during the colder months of the year, dropping its leaves, and watering should be considerably decreased to avoid rot (2,3,4).
Soil: This plant can tolerate poor soil but requires well-draining soil and drying out of the medium between watering (2,3,4,5,6). A potting medium formulated for cacti and succulents is suitable (3,7).
Lighting: Red monadenium needs bright light to thrive and will tolerate intense direct sun, but develop a reddish coloration on its foliage in response (2,3,4).
- It will not tolerate deep shade, as this will cause leggy growth and increase the risk of rot (2,3,4).
Propagation: Red monadenium can be propagated vegetatively or by seed, however vegetative practices are more common as the seeds can be difficult to germinate (2,3,6).
Cold Tolerance: This plant has a minimum cold hardiness of 30 degrees and prefers to be in USDA zones 10b-11b (3,4,6).

Special Accommodations: This plant typically flowers during the summer however spontaneous blooms occur throughout the year (2.7).
- Care should be taken during cutting propagation and pruning as the plant’s sap is toxic, causing irritation to the skin and eyes (2,3,4,5).
- Red monadenium can benefit from applying a balanced 10-10-10 fertilizer (diluted to ¼ strength) once a month during the growing season (3).
- This plant will not need to be repotted very often, only when it appears to be outgrowing it (3,6).
- Due to the aesthetic quality of its root system being a major attraction for bonsai enthusiasts, it should be noted that this plant’s caudex is concealed in its early years, and it won’t develop this prized feature until it matures, however under-potting can help bring it to the surface (2,4,7).

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