C3 plants

Also: C3

Plants that produce a three-carbon compound during photosynthesis, including most trees and agricultural crops such as rice, wheat, soybeans, potatoes and vegetables.

C3 photosynthesis seems to be the oldest form of the process of photsynthesis, possibly existing for billions of years.  It is less efficient than other forms of photosynthesis such as C4.

Definition based on (revised from) IPCC AR4.