Short and reticulately-pitted tracheal cells, similar to tracheids, often occur in the circummedullary region of cycadean stems. In an old stem of Cycas, Encephalartos or Macrozamia the secondary wood consists of several rather unevenly concentric zones, while in some other genera it forms a continuous mass as in conifers and normal dicotyledons.
Dichotomously branched as in Macrozamia heteromera.
Of Cycads, Australia and New Caledonia have Cycas, and the former the endemic Macrozamia and Bowenia.
Among existing types the genus Macrozamia appears to show the nearest approach to this simpler structure of the leaf-traces.