Pencil Tree (Euphorbia tirucalli) Sap: A Serious Eye Hazard

The white sap of pencil tree (Euphorbia tirucalli) is highly caustic—eye contact can cause corneal damage and blindness. All Euphorbia species (including poinsettia) should be treated as irritants. Elephant ear and other aroids (spathiphyllum, dieffenbachia, caladium) contain calcium oxalate crystals causing severe oral irritation. Plants defend themselves chemically, not just with thorns.