This molecule is a hydrocarbon with a faint odor when it is at its pure stage. This molecule is a colorless flammable gas widely used in the chemical industry. It is the second simplest unsaturated hydrocarbon and the first simplest alkene. It is also a very important natural plant hormone. It is used to force fruit to ripen in agriculture. Ethylene can both stimulate and regulate the ripening of fruit, the shedding of leaves, and the opening of flowers. It acts at trace levels throughout the entire life of a plant. Plants produce ethylene at certain stages of growth that include ripening of fruits, germination, senescence of flowers, and abscission of leaves but it can also be induced through wounds, chemicals, and environmental stresses.