Cassava, bean, and maize leaves were fed with (14)CO2 in light; the primary products of photosynthesis were identified 5 and 10 s after assimilation. In cassava, approx. 40-60 percent were incorporated in C4 acids with 30-50 percent in phosphoglyceric acid, which indicates that cassava possesses the C4 photosynthetic cycle. However, due to the lack of typical Kranz anatomy, appreciable C assimilation takes place directly through the Calvin- Benson-Bassham cycle. (AS (extract)