What are plants and how are they defined?

All plants on this earth belong to Kingdom Plantae. Kingdom Plantae is a group that includes autotrophic, multicellular, photosynthetic eukaryotes. These are mainly non-motile, embryo forming, and function primarily as the producers in the ecosystem because they can fix solar energy in chemical energy through photosynthesis. They have a rigid cell wall mainly made up of cellulose.