The Voynich Codex, one of the most fascinating and bizarrely illustrated manuscripts in the world, is preserved in the Beinecke Rare Book and Manuscript Library of Yale University. The descriptive text seems to be an un‐deciphered writing system. The manuscript has been divided into sections by Voynich commentators, with the major portion of the manuscript depicting plant, animal, and geological images. In 1944, Hugh O'Neill, a distinguished taxonomic botanist at the Herbarium of the Catholic University of America in Washington, DC, identified two Mesoamerican plants, indicating the possibility that this manuscript is post‐Columbian. These identifications were expanded to include 37 plants of Colonial New Spain. This chapter extends these identifications to 59 phytomorphs, encompassing 55 plant species. Phytomorphs were analyzed by comparing the morphology of the botanical illustrations with herbarium specimens, photographs, and contemporary sources of live plants.