Convergent traits are species-specific and evolve over long periods to adapt to geographic changes. The traditional forward genetics methodology, based on hybrid populations, may be insufficient to study these traits. We applied single-cell omics, spatial omics, and evolutionary genomics approaches to fill the gap in understanding these traits, such as C₄ photosynthesis, CO₂ concentration mechanisms that have convergently evolved with over 60 origins. We focus on C₃ and C₄ species in Poaceae, Cyperaceae, Amaranthaceae, and Molluginaceae, to address questions about how historical geographic changes triggered C₄ evolution and how C₄ genetic elements evolved in distinct species.