Anatomical types of leaves and assimilating shoots and carbon C/C isotope fractionation in Chinese representatives of Salsoleae s.l. (Chenopodiaceae)

To examine the anatomical types in Salsoleae s.l., and evaluate carbon isotope fractionation values for identifying the respective photosynthetic pathway, a total of 34 species representing 12 genera of Salsoleae s.l. in China were examined using light microscopy and carbon ¹³C/¹²C isotope fractionation. There are nine leaf anatomical types, namely, Sympegmoid (Sympegmoid type, Sympegmoid type II), Salsoloid with hypodermis (Salsola soda type, Salsola soda type II, Nanophyton type II), Salsoloid without hypodermis (Salsola kali type, Salsola kali type II, Nanophyton type, Climacoptera type II). Salsola soda type and Salsola soda type II are found in the assimilating shoots. Two new subtypes, Salsola soda type II and Nanophyton type II are reported. Anabasis brevifolia, A. eriopoda, A. elatior, A. truncata and A. salsa are of the Salsola soda type II, with a distinctive two-layered epidermis cells. Horaninowia ulicina is of the Nanophyton type II with hypodermis which distinguished from Nanophyton type; Both, Salsola kali type and Climacoptera type II exist in Climacoptera. The Climacoptera type II is distinguished from Climacoptera type by an adaxially interrupted Kranz layer. Salsola collina, S. zaidamica, S. praecox, S. pellucida and S. ruthenica in Salsola sect. Salsola have the Salsola kali type II. The Salsola kali type differs from Salsola kali type II having the palisade and Kranz cells interrupted by longitudinal collenchymatic ridges. Although carbon isotope fractionation data alone are already useful tools to identify photosynthesis, their determination in combination with other approaches, such as anatomical studies are necessary in order to render a structuring of all possibilities evolved among C₄ type Chenopodiaceae.