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.