Plastids are double membrane bounded organelles present only in plant cell.

Plastids are double-membraned organelles found in the cells of plants and algae. They are involved in various functions such as photosynthesis, storage of food and pigments, and synthesis of lipids. Plastids contain their own DNA and are thought to have originated from endosymbiotic cyanobacteria.

There are three main types of plastids:

1. Chloroplasts: These are green plastids that contain chlorophyll and are responsible for photosynthesis. They convert sunlight, carbon dioxide, and water into glucose and oxygen.

2. Chromoplasts: These are colored plastids that contain pigments other than chlorophyll, such as carotenoids. They are responsible for the synthesis and storage of pigments, giving fruits and flowers their vibrant colors.

3. Leucoplasts: These are colorless plastids that store starch, lipids, proteins, and other nutrients. They are found in non-photosynthetic tissues such as roots and seeds.

Plastids can differentiate into different types depending on the needs of the cell. For example, undifferentiated plastids called proplastids can differentiate into chloroplasts or other types of plastids depending on the environmental conditions and cellular requirements.