The authors seek to show how acid solutions of anthocyanins may by color comparisons facilitate phylogenetic investigations. By this method the anthocyanin constitution of plants may be revealed preliminary to large scale analyses. Flower colors are not as reliable indiees as acid extracts observed at boiling point. This is because of co-pigments which exist for all anthocyanins. One of the most powerful of these co-pigments is the glucoside of 2-hydroxy-xanthone. It is believed that the formation of these complexes occurs in nature influencing variations in flower color. Color variations in species are thought not to be due to changes in pH but to changes in anthocyanin and its co-pigment complexes. All studies here reported were made with cold HC1 extracts compared with known standards of the suspected anthocyanin. Briefly the HC1 solutions after boiling are extracted with amyl alcohol. This solution is washed and portions shaken with 5% picric acid in one volume of amyl ethyl ether and 4 volumes of anisole. Color characteristics and reactions of the following anthocyanidins and anthocyanins are listed: Pelargonidin, pelargonin; peonidin, peonin; cyanidin, cyanin; maloidin, malvin; petunidin, delphinidin, hirsutidin. A list of observations on co-pigments is also appended.