The major group of organisms considered to be producers are plants.

Here's why:

* Photosynthesis: Plants are the primary producers in most ecosystems. They use sunlight, water, and carbon dioxide to create their own food through photosynthesis.

* Energy Source: This process converts light energy into chemical energy (sugars), which forms the basis of the food chain.

* Foundation of Ecosystems: Plants provide the energy that fuels all other organisms in an ecosystem.

While some other organisms can also perform photosynthesis (like algae and certain bacteria), plants are the dominant and most recognizable group of producers on land.