Onion (and its relatives) and horseradish (and its relatives) store the components of a sulfur-based binary chemical weapon to deter being eaten by animals. Whe

Onion (and its relatives) and horseradish (and its relatives) store the components of a sulfur-based binary chemical weapon to deter being eaten by animals. When the tissue is ruptured, the chemical deterrent is formed and released. However, the compound breaks down with time, oxygen, heat, etc.