Green plants are called producers because they produce their own food through a process called photosynthesis. Here's a breakdown:

• Photosynthesis: Plants use sunlight, water, and carbon dioxide to create their own food in the form of glucose (sugar). This process occurs in the chloroplasts, which contain chlorophyll, giving plants their green color.
• Producers in the Food Chain: Because plants create their own food, they form the base of most food chains and ecosystems. They provide energy for other organisms that cannot produce their own food.
• Energy Source: The energy stored in plants through photosynthesis is then transferred to other organisms when they consume the plants.

In essence, green plants "produce" the initial energy and organic compounds that sustain most life on Earth.

For further reading, you can refer to these resources:

• Science Learning Hub - Photosynthesis
• Britannica - Producer (Organism)