Do all aquarium plants need CO2 injection?

All aquatic plants need CO₂ as one of their basic building blocks to survive and grow. However, some types like cryptocoryne plants are fine with the normal amounts of dissolved CO₂ found in aquarium water and do not need extra CO₂, while other plants like scarlet temple could benefit from CO₂ injection but don’t require it. A third category of plants — which includes Blyxa japonica, dwarf hairgrass, and dwarf baby tears and other similar carpeting plants — has higher demands and necessitates the use of CO₂ injection for the best chances of success. 

For more information on CO2 systems in high tech planted tanks, read the full article.