Eucommia is a genus of small trees now native to China, with a fossil record that shows a much wider distribution.

E. constans is one of five described fossil species from North America assigned to the modern genus Eucommia.

[1] Eucommia constans was first identified by Susana Magallón-Puebla and Sergio R. S. Cevallos-Ferriz in 1994 from the Miocene to Pleistocene Pié de Vaca Formation which outcrops in the state of Puebla in East-central Mexico.

[2] The species was described from a group of over one-hundred and fifty compression fossils studied by Magallón-Puebla and Cevallos-Ferriz who published their findings in an International Journal of Plant Sciences article.

E. eocenica is larger than E. constans and is notably different in the structure of the fruit tip, which is distinctly pointed rather than rounded as seen in E.