DISTRIBUTION OF KRANZ SYNDROME AMONG ASTERACEAE

A broad survey of the Asteraceae, involving visual characters, was undertaken to ascertain the occurrence of possible Kranz-type (C₄) plants. One hundred and seven taxa representing 51 genera were examined by mass spectrometry for their ¹³C/¹²C ratios in dried leaf tissue. Species possessing the high ¹³C/¹²C ratio typical of the Kranz syndrome were found in genera belonging to the following tribes: Heliantheae (subtribe Coreopsideae)—Chrysanthellum (4 spp.), Eryngiophyllum (1 sp.), Glossocardia (1 sp.), Glossogyne (1 sp.), Isostigma (5 spp.); Tageteae—Pectis (21 spp.); and Helenieae—Flaveria (4 spp.). The only genus to possess both C₃ and C₄ species was Flaveria in which all but four species appear to possess a C₃-type metabolism. When appropriate, the phyletic input of these data is discussed.