C4 photosynthesis. The GO class 'C4 photosynthesis' is restricted for use with gene products from species of the taxonomic grouping Viridiplantae. This is a narrower taxonomic group than that to which the GO superclass 'photosynthesis' is restricted. The GO class 'photosynthesis' is restricted for use with gene products from any sub-type of the Viridiplantae, Euglenozoa, Archaea or Bacteria. The relationship between 'photosynthesis' and these four taxonomic groups is shown by the relationship only _in _taxon from 'photosynthesis' to the union term 'Viridiplantae or Euglenozoa or Archaea or Bacteria', and by the relationships between this union term and the four individual taxonomic groups. These latter relationships are shown as union _of relationships (marked 'un'). In this figure, the GO classes are shown in blue, and the taxonomic classes are shown in yellow. The relationship types are labeled in the diagram.