Cycads are a group of plants that can trace their origins back 200-300 hundreds of years. Although it would be incorrect to say that they are unchanged from those times, they do still retain characteristics and appereance of old ancestors as seen in fossiles. There are around 200 species of cycads, warm parts of the world.

Dioon spinulosum is a cycad, belong to Zamiaceae family and dioon genus. It is one of the tallest cycads in the world also the largest American cycad. It can be grown up to 15 m in height and 30 cm diameter trunk. The giant dioon is endemik to limestone cliffs and rocky hillsides in the evergreen tropical rainforests in Mexico (Oaxaca, Veracruz, Yucatan) up to 450 m above sea level. The genus name Dioon comes from the Greek, meaning “two eggs”, because the seeds are borne in pairs. The species name of spinulosum is derived from the Latin, meaning spiny.

Giant Dioon has shiny, stiff, bright green leaves that grow in an upright manner.  Its pinnate (feather shaped) leaves are 150-200 cm long and extend radially out from the trunk. Each leaf carry 150-250 leaflets on. These leaflets are flat, with small marginal thorns tapering to a sharp point.

Dioon spinulosum is dioecious like all cycads, male and female plants needed to produce viable seeds. The female cones are 30 cm or more in length and covered with a dense wool. Seeds are cream to white colored, oval shaped and approximately 4-5 cm long and 2-3 cm wide.

Giant Dioon prefers a subtropical or tropical climate, and partial shade or filtered sun. Mature and established plants have been reported to tolerate temperatures down to -4ºC for short time periods, without incurring significant foliage damage. It handles moisture and humidity better than most cycads, but must be kept in well-draining soil like nearly all cycads. Although tolerant of poor soils, the giant dioons growth can be greatly improved through the application of fertilizers.

In cultivation, Dioon spinulosum is one of the most trouble free cycads. Seedlings grow rapidly and in the span of a few years can become sizeable plants. Plants do better if placed in a somewhat shady location with dampness at the roots at all times. Giant Dioon has few pest problems. Occasionally, infestations of mealybugs or scale insects occur but generally only when the plant is in a stressed condition.

Dioon spinulosum may be propagated by seeds or by division and replanting of the offsets formed at the base of the plant. The leaves of the plant are used in decorations and floral arrangements.

Use in landscape: A single large Giant Dioon can be an excellent feature plant in a tropical or desert landscape, in any garden in warm temperate to tropical climates. Often substituting for a true palm where a large crown is desired without a tall trunk. Dioon spinulosum can also have a spectacular place in a small garden where space is limited. It also makes an exotic striking understory plant beneath large trees or any structure that allows at least partial sunlight to pass through.

A striking approach is to follow, with large paired plants in containers or feature beds that flank driveways, doorways or gates. Giant Dioon is also wonderful as a tub plant in a brightly lit spot in the home, on a porch or deck, or in a conservatory.