Species in the genus Dioon have 2n = 18 chromosomes. Disturbances alter the population dynamics of "Dioon edule" populations. Both subspecies of "Dioon edule" are on the verge of becoming endangered. Pollination of "Dioon" by wind pollination or by animals, has not yet been determined. Dioon stevensonii is a species of cycad native to Mexico. "Dioon spinulosum" prefers well-drained soil with regular water. "Dioon edule" is endemic to the eastern coast of Mexico. Dioon sonorense is a species of cycad native to northern Mexico. Dioon rzedowskii is a species of cycad that is native to Oaxaca, Mexico. "Dioon edule" and "Dioon tomasellii" have the most widespread ranges. Dioon is a genus of cycads in the family Zamiaceae. Dioon merolae is a species of cycad that is native to Chiapas and Oaxaca, Mexico. The genus name "Dioon" means "two-egged", referring to the two ovules (see photo below). Dioon can get very old, maybe even over 1000 years. "Dioon" would therefore be the basal genus of the family.