Leaves of Artemisia annua L. are a plentiful source of artemisinin, a drug with proven effectiveness against malaria. The aim of this study was to classify the photosynthetic mechanism of A. annua through studies of the carbon isotope composition (delta 13C) and the leaf anatomy. A. annua presented a delta 13C value of - 31.76 ± 0.07, which characterizes the plants as a typical species of the C3 photosynthethic mechanism, considering that the average delta 13C values for C3 and C4 species are -28 and -14, respectively. The leaf anatomy studies were consistent with the delta 13C results, where, in spite of the existence of parenchymatic cells forming a sheath surrounding the vascular tissue, the cells do not contain chloroplasts or starch. This characteristic is clearly different from that of the Kranz anatomy found in C4 species.
C3 and C4 plants; isotope discrimination; Kranz anatomy; photosynthesis
