CROWN-OF-THORNS (KOEBERLINIA SPECIES; EUPHORBIA SPECIES)
Crown of thorns is a house and garden ornamental, native to Madagascar. It is named for a legend that identifies it as the plant from which Roman legionaries made the mock crown placed on Christ’s head at his crucifixion. In remembrance of the legend, the long stems of crown of thorns are sometimes deliberately trained to grow in a crown-like shape.
Because these plants are so prickly, accidental poisonings are rare, but it is worth wearing gloves while tending them, not only to avoid the thorns, but also to prevent direct contact with the milky sap, which contains the greatest concentration of poison. A thumb-prick from the thorns is not dangerous, provided the usual precautions for minor wounds are taken.
Succulent spiny plants of the spurge family are mistakenly called cacti, to which they are not closely related.
All parts of the plant that contain sap, though the sap itself is most toxic. Even dried plant materials retain their poisonous properties.
Volatile oils, resins, alkaloids, and glycosides: quite a cocktail of bad stuff.
TYPICAL POISONING SCENARIO
Children and others sometimes mistake the seedpods, which resemble capers, for the edible fruit of other plants. Children have been fatally poisoned by sun spurge seeds, for example. Another possibility is medical abuse; there is a case on record in which a woman used snow-on-the-mountain as an abortive, with fatal results. Luckily, in most species, the sap tastes so bitter that few victims persist in eating these plants long enough to be seriously affected.
All spurges cause vomiting, nausea, and/or diarrhea if they are eaten. If that’s not enough to keep you away, consider that handling some species, such as crown of thorns and poinsettia, can cause skin rashes, blistering, and eye irritation (remember your mother telling you, “Don’t rub your eyes with those dirty fingers”?). High doses result in intense burning of the mouth, throat, and stomach; uncontrollable salivation; convulsions; and sometimes, coma and death. So, grow the pretty plants in your house or garden, but wear gloves to prune them and discourage the cat from trying a bit of salad, please.
CROWN-OF-THORNS POISON INFORMATION
Resins and Volatile Oils
Resins and volatile oils are derived mostly from hydrocarbons—chemicals composed of hydrogen, carbon, and oxygen. This group of poisons is very diverse.