oxytocin: hormone secreted by the posterior pituitary gland (trade name Pitocin); stimulates contractions of the uterus and ejection of milk
hormone: the secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect
pneumatophore: an air-filled root (submerged or exposed) that can function as a respiratory organ of a marsh or swamp plant