This is the most primitive extant gymnosperm order and contains upwards of 206 species.
The gymnosperms have been subdivided along a variety of different lines and the recent flood of information on fundamental taxonomic characters (such as chloroplast DNA) has led to further revisions. The principal point of contention between various schemes for dividing gymnosperms above the family level seems to be at what point in the hierarchy are distinctions to be made. The cycads are variously treated as a phylum, subphylum or order within the gymnosperms.