The pigment plants have that they use for photosynthesis is called .

chlorophyll

Explanation:

The mechanism by which light energy can be transformed into chemical energy by synthesis of organic compounds is chlorophyll, a member of the most significant pigment class involved in photosynthesis. In nearly all photosynthetic species, e.g. green plants, cyanobacteria and algae, the use of chlorophyll is identified. It consumes light energy and is then used for the conversion to carbohydrates of carbon dioxide.