Starch is a polymeric carbohydrate (polysaccharide) which consists of numerous glucose units and produced by most green plants for energy storage.

In photosynthesis, plants use light energy to produce glucose from carbon dioxide. The glucose is used to generate the chemical energy required for general metabolism, to make organic compounds such as nucleic acids, lipids, proteins and structural polysaccharides such as cellulose, or is stored in the form of starch granules, in amyloplasts. Toward the end of the growing season, starch accumulates in twigs of trees near the buds. Fruit, seeds, rhizomes, and tubers store starch to prepare for the next growing season. - Wikipedia

Amylases are the enzymes that break down (hydrolyze) starch into sugars. are known as .

• Alpha-amylases are found in plants and in animals.
  Human saliva is rich in amylase, the pancreas secretes it.
• Beta-amylase cuts starch into maltose units during digestion.