Rzedowski worked at
Syntex in 1953. From 1954 to 1959 he was appointed a professor at
Universidad Autónoma de San Luis Potosí and director of that University's Instituto de Investigación de Zonas Desérticas. In 1959 he moved to the Colegio de Postgraduados de Chapingo, Mexico as professor-investigator and then in 1961 was appointed professor at the Escuela Nacional de Ciencias Biológicas del Instituto Politecnico Nacional, where he remained until 1984. He then founded the Centro Regional del Bajío, Instituto de Ecología, Pátzcuaro, Michoacán. At the time he started to work on Mexican
floristics, very few studies were published in that field, so he became a pioneer in it. His research has involved extensive fieldwork. Afterwards, he became the most respected botanist in Mexico. He explored a lot of places surveying the local plant life and collected more than 50,000 specimens that can be found in many herbaria. He has also contributed significantly to the taxonomy of Burseraceae and Compositae. Rzedowski also provided leadership to the botanical community in Mexico and internationally. He was significant in the re-development of the Sociedad Botanica de Mexico and he organized the First Mexican Botanical Congress in 1960. In 1988 he launched the scientific journal Acta Botánica Mexicana. ==Personal life and death==