Gaseous hormone Produced in the actively growing meristems of the plant; in senescing, ripening or ageing fruits; in senescing (ageing or dying) flowers, in germinating seeds and in certain plant tissues as a response to bending, wounding or bruising. as a gas, diffuses readily throughout the plant. May promote leaf senescing and abscission (leaf fall). Increases female flowers in cucumbers (economically - will increase fruit production). Degreening of oranges, lemons and grapefruit – ethylene gas breaks down chlorophyll and lets colors show through.