Guaiacum coulteri

The Aztecs made a blue/green pigment from the flowers of Guayacum coulteri. They called the color matlali.

In Alamos, the brilliant blue flowers blossom in May. The Seri Indians of Sonora used the resin of guayacan to make a pigment called Seri Blue. The Seri process involved the combination of organic and inorganic chemistry, thus it is analogous to ancient Maya pigment technology.