Essential nutrients are chemical elements that are necessary for plant growth. An element is essential for plant growth when: 1) it is required for a plant to complete its life cycle (to produce viable seeds); 2) it is part of a molecule or component of the plant that is itself essential to the plant, such as the magnesium in the chlorophyll molecule; and 3) the plant displays symptoms of deficiency in the absence of the element. Essential nutrients are also referred to as essential minerals and essential inorganic nutrients.