For example , Haeckel placed the red algae ( Haeckel 's Florideae ; modern Florideophyceae ) and blue-green algae ( Haeckel 's Archephyta ; modern Cyanobacteria ) in his Plantae , but in modern classifications they are considered protists and bacteria respectively . For example , Haeckel placed the red algae ( his Florideae , modern Florideophyceae ) and blue-green algae ( his Archephyta , modern Cyanobacteria ) in his Plantae .