The phytohormone (plant hormone) ethylene is an important signaling molecule that is involved in many plant processes including, but not limited to, abscission (the physiological process promoted by abscisic acid whereby plants shed a part), leaf and flower senescence, germination, sex determination, and fruit ripening. Ethylene also functions in both biotic and abiotic stress responses. Exposure to environmental stresses—such as flooding, wounding, herbivory (the consumption of plants without killing them), chilling, or pathogen attack—can enhance ethylene production. This ethylene then slows growth until the stress is removed. Interest in ethylene's importance as a plant hormone has resulted in thousands of peer-reviewed publications in the last 100 years and has laid the foundation for a real understanding of ethylene's involvement in plant growth and development.