Pencil Tree

Euphorbia tirucalli is native to tropical and subtropical regions of Africa and the Indian subcontinent.

• Original native range extends across eastern, northeastern, and tropical southern Africa, from Kenya and Tanzania southward through Mozambique and into northeastern South Africa
• Also native to parts of India, particularly the western coast (Malabar region) and dry areas of the Deccan Peninsula
• Occurs at elevations from sea level to approximately 1,500 meters
• Grows in dry thorn scrub, bushveld, rocky hillsides, and coastal bush in hot, semi-arid to subhumid climates
• Widely naturalized throughout the tropics, including Southeast Asia, the Pacific Islands, Central America, the Caribbean, and northern Australia
• First described by the Swedish botanist Carl Linnaeus in 1753
• Has been spread by humans for centuries as a living fence, medicinal plant, and ornamental

Euphorbia tirucalli is a large, much-branched, nearly leafless succulent shrub or small tree.

Stems:
• Cylindrical, smooth, pencil-thin, approximately 5 to 8 mm in diameter
• Bright green when young, maturing to darker green or grayish-green
• New growth and stress colors can turn brilliant orange-red to coral-pink (especially in the cultivar "Fire Sticks")
• Branch profusely from the base and along main stems in a candelabra-like pattern
• Main trunk and older branches become woody and brown with age, reaching 5 to 12 cm in diameter

Leaves:
• Tiny, linear, 1 to 2.5 cm long and only 1 to 2 mm wide
• Present only briefly on new growth, dropping quickly
• Functionally insignificant — photosynthesis occurs in the stems

Flowers:
• Minute, yellow-green cyathia (the characteristic Euphorbia inflorescence) approximately 5 to 7 mm in diameter
• Produced in clusters at branch tips, primarily in spring to summer
• Individually inconspicuous but can be numerous
• Male and female flowers borne on the same plant (monoecious)

Fruit:
• Small, three-lobed capsules approximately 5 to 6 mm in diameter
• Green ripening to brown, explosively dehiscent

Size:
• In cultivation typically 2 to 5 meters tall
• In optimal tropical conditions can reach 8 to 12 meters as a small tree

The milky latex sap of Euphorbia tirucalli is highly toxic and represents the primary hazard associated with this plant.

Toxic compounds:
• Contains diterpene esters (including 4-deoxyphorbol esters) that are potent skin and mucous membrane irritants
• The latex is a known tumor promoter and co-carcinogen

Effects on skin:
• Contact with the latex causes immediate burning pain, redness, and blistering
• Severe contact dermatitis may develop within hours
• Prolonged or repeated exposure increases sensitivity

Effects on eyes:
• Sap contact with the eyes is a medical emergency — can cause intense pain, corneal abrasion, and potentially permanent vision damage or blindness

If ingested:
• Causes burning of the mouth and throat, nausea, vomiting, abdominal pain, and diarrhea
• Large ingestions may lead to more severe systemic effects

Safety precautions:
• Always wear gloves and eye protection when handling or pruning this plant
• Wash tools thoroughly after use
• Keep away from children and pets
• Do not touch face or eyes after handling

The Pencil Tree is surprisingly easy to grow but demands respect for its toxic sap.

Soil and site:
• Requires well-drained soil — a cactus/succulent mix or sandy loam with added grit is ideal
• Full sun to partial shade; best color development occurs in full sun
• Suitable for USDA hardiness zones 10 to 12; damaged by temperatures below 5°C
• Often grown as a container plant in cooler climates, moved indoors during winter

Watering:
• Highly drought-tolerant; water only when the soil is completely dry
• Reduce watering to monthly in winter
• Overwatering causes root rot — the most common cause of death in cultivation

Propagation:
• Easily propagated from stem cuttings at any time of year
• Cuttings should be allowed to callus (dry and seal) for 3 to 7 days before planting to prevent rot
• CAUTION: Wear gloves and eye protection when taking cuttings; the latex flows freely from fresh cuts
• Root readily in dry, sandy medium without rooting hormone
• Can also be grown from seed, though this is less common

Pruning:
• Prune to shape or control size, always wearing protective gear
• Sealed cuts with the latex can be dusted with sulfur or cinnamon powder to prevent fungal infection