Although superficially resembling palms and tree-ferns, cycads differ in reproductive behaviour (5). All are dioecious, with separate male and female plants, and all produce seeds with a fleshy outer coat (sarcotesta) surrounding a hard, stony layer (sclerotesta). The fleshy coat is attractive to animals, which act as dispersal agents. Like all cycads, Dioon edule does not produce flowers, instead bearing the reproductive organs on cones, which are formed from modified leaves. Although previously believed to be wind-pollinated, cycads are now known to be mostly pollinated by insects such as beetles (2) (5) (8). The female cone of Dioon edule measures up to about 29 centimetres in length, while the male cone is slightly smaller, at up to 20 centimetres (2). The seeds are relatively large, at around 2.5 to 4.5 centimetres in length (5). All cycads are slow-growing and long-lived (5) (8), and, as in other Dioon species, the female Dioon edule only produces a single cone at each reproductive cycle (2).
In addition to normal roots, cycads possess specialised roots containing cyanobacteria, which form a symbiotic relationship with the plant, providing it with extra nutrients by converting (fixing) atmospheric nitrogen into a usable form. Cycads also posses roots which can be retracted for protection against fire and drought (2) (5).