Why are many Euphorbiaceae plants poisonous?

Many plants within the Euphorbiaceae family are poisonous due to the presence of various toxic chemical constituents, including alkaloids, glycosides, resins, and toxalbumins. These substances are often concentrated in the plant's milky latex, leaves, or fruits, serving as a defense mechanism.12

The toxicity varies by species and can manifest through ingestion or physical contact:

• Ingestion: Certain species contain highly potent toxins. For example, the castor bean contains ricin, a toxalbumin that is among the most toxic substances known. Cassava contains cyanophoric glycosides, which can be fatal if not properly processed.1
• Contact: The milky sap of many Euphorbia species and the manchineel tree can cause severe skin blistering, eye irritation, and even blindness. Some genera, such as Dalechampia, Tragia, and Cnidosculus, possess stinging hairs that inject irritating substances into the skin.312

While these compounds are dangerous, they are also the source of various medicinal and industrial applications, such as purgatives, rubber, and traditional remedies.32