A screening of the dicotyledonous weed flora for the occurrence of C4 dicarboxylic acid pathway of photosynthesis

Abstract

Using the criteria of leaf anatomy, carbon dioxide compensation point and photosynthetic rate under reduced oxygen tension, a number of the local herbaceous and dicotyledonous weeds were screened for the occurrence of the C4 pathway of photosynthesis. Of the thirty-two species, belonging to nine families seventeen species revealed the characteristics of the C4 plants. All of the plants surveyed here were hitherto not tested and therefore the present results extend the number of plants already known to possess the Hatch-Slack pathway of photosynthesis. Another noteworthy feature of the investigation was the finding of interspecific differences within the generaHeliotropium, Alternanthera, Mollugo andEuphorbia in the presence or absence of the C4 pathway.