Photosynthesis in <i>Salsola</i> Species (Chenopodiaceae) from Southern Africa Relative to their C₄ Syndrome Origin and their African‐Asian Arid Zone Migration Pathways

Abstract: Over 60 Salsola species of Chenopodiaceae from South Africa were studied for their photosynthesis type, using δ 13 C analysis and light microscopy of leaf anatomy. These species cover about 70 % of the total list of Southern African Salsola species and grow naturally in South and Southwest African desert regions. All species are shrubby forms and belong to the single subsection Caroxylon. Only C 4 photosynthesis was found in the Salsola species determined with 13 C/ 12 C carbon isotope discrimination values that ranged from ‐ 11.04 to ‐ 14.03 % (PDB), plus the presence of a Kranz type assimilation tissue anatomy. The apparent absence of C 3 in Salsola in South and Southwest Africa and the known presence of C 3 and C 3 ‐ C 4 intermediate photosynthesis in Caroxylon, Salsola species in Asia strongly indicate that the genus Salsola originated in Asia and later migrated to South Africa.

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