The objective of this study was to characterise photosynthesis in terrestrial non-Kranz (NK) C₄ species, Bienertia sinuspersici Akhani and Suaeda aralocaspica (Bunge) Freitag & Schütze (formerly Borszczowia aralocaspica), compared with closely related Kranz type C₄ Suaeda eltonica Iljin and Suaeda taxifolia Standley, and C₃ species Suaeda heterophylla Bunge and Suaeda maritima Dumort in subfamily Suaedoideae (Chenopodiaceae). Traditional Kranz type C₄ photosynthesis has several advantages over C₃ photosynthesis under certain environmental conditions by suppressing photorespiration. The different photosynthetic types were evaluated under varying levels of CO₂ and light at 25°C. Both NK and Kranz type species had C₄ type CO₂ compensation points (corrected for dark-type respiration) and half maximum saturation of photosynthesis at similar levels of atmospheric CO₂ (average of 145 µbar for the C₄ species v. 330 µbar CO₂ for C₃ species) characteristic of C₄ photosynthesis. CO₂ saturated rates of photosynthesis per unit chlorophyll was higher in the C₃ (at ~2.5 current ambient CO₂ levels) than the C₄ species, which is likely related to their higher Rubisco content. The amount of Rubisco as a percentage of total protein was similar in NK and Kranz type species (mean 10.2%), but much lower than in the C₃ species (35%). Light saturated rates of CO₂ fixation per unit leaf area at 25°C and 340 µbar CO₂ were higher in the Kranz species and the NK C₄ S. aralocaspica than in the C₃ species. In response to light at 340 µbar CO₂, there was a difference in rates of photosynthesis per unit Rubisco with NK > Kranz > C₃ species. There were no significant differences between the three photosynthetic types in maximum quantum yields, convexity of light response curves, and light compensation points at 25°C. The water use efficiency (CO₂ fixed per water transpired) at 340 µbar CO₂, 25°C and 1000 µmol quanta m^–2 s^–1 was on average 3-fold higher in the C₄ (NK and Kranz) compared with the C₃ species. The results show that the NK species have several C₄ traits like the Kranz type species in subfamily Suaedoideae.