The planting hole for a cycad should be dug several inches wider and deeper than its root ball. Some loosened dirt is placed in the bottom of the hole so that the soil line of the root ball is equal to the grade of the surrounding soil. The hole is then filled to just below its upper edge.
There is a kind of root found in cycads known as a coralloid root. These roots branch off the tap root or secondary roots and are distinctive in that they grow laterally or upward, forming a nodular mass at the apex. These coralloid roots occur slightly below or slightly above the soil surface and generally contain cyanobacteria, also known as blue-green algae. Cyanobacteria are able to fix atmospheric nitrogen and make it available as a nutrient to the cycad. The ability to extract this important nutrient from the air explains how many cycad species are able to survive on almost sterile soils.
Morphology and Reproduction of Cycads
Cycad stems are of two general kinds, arborescent or subterranean. Arborescent stems are topped by a crown of pinnately divided leaves, giving the plants the general appearance of palms. Arborescent cycads are easy to distinguish from palms because cycad stems are usually covered with an armor of persistent leaf bases and reduced, scalelike leaves called cataphylls where as palm stems are generally smooth and circled by old leaf traces.
Cones are the reproductive organs of cycads and are composed of highly modified leaves known as sporophylls that are spirally aggregated into a conelike structure. All cycads are dioecious-any individual plant is either female or male. The only cycads without sporophylls aggregated into true cones are females of the genus Cycas, which have either tightly overlapping or open and pendant sporophylls.