We describe the occurrence of arbuscular mycorrhizae in the roots of Zamia pumila and Dioon edule. Seedlings were grown on native, unsterilized soil taken from local pinelands of south Florida, where Z. pumila occurs naturally. Arbuscules, hyphae, hyphal coils, and vesicles occur in the parenchyma cells of the root cortex, especially the half of the cortex next to the stele. Hyphae of the arbuscular mycorrhizal fungi (AMF) occur mainly in longitudinal intercellular spaces and conform to the Acorus type. The finest, ultimate roots have AMF, but these roots are extremely brittle, detach with the slightest disturbance, and are usually lost when plants are uprooted from the ground. No AMF were found in the cortex of coralloid roots. Vovides (1991) previously reported that AMF occur on Dioon edule and Ceratozamia mexicana, and we reconfirm this in D. edule. In this species, AMF appear to be mostly associated with the outer and to a lesser extent the inner cortex. However, roots of a potted plant of C. hildae growing in native soil lacked AMF. When grown on low phosphorus soils, legumes are known to require AMF in order for their Rhizobium nodules to fix nitrogen. Without AMF, the legumes are deficient in phosphorus, which inhibits nodule production and nitrogen fixation. It is probable that cycads, with their nitrogen-fixing coralloid roots containing Nostoc, may also require AMF for successful nitrogen fixation when phosphorus is limiting.