Dioon

Dioon dioecious shrubs, with cylindrical stem, usually with many leaves and petioles they are persistent or deciduous. The genre is often divided into two groups of different morphology. in the first group: D. mejiae, D. rzedowskii, D. spinulosum, “usually characterized by large fronds, well developed trunks, and massive cones”. Elsegundo group contains : D. califanoi, D. caputoi, D. edule, D.holmgrenii, D.merolae, D. purposes, D. sonorense, D. tomasellii, and they are “less robust, with generally less large trunks,considerably lower fronds, and with smaller leaves. Pinnate leaves, spirally arranged, with non-articulated leaflets and their lower leaflets often reduced to spines.