Since my publishing a taxonomic revision of the genus Cycas in 1998 there has been a virtual explosion in the study of this genus, particularly by Ken Hill and also by Chinese botanists.  More precisely, this began in 1992 with Hill’s work on Queensland, but I had not had the opportunity to go to Australia and look at the new material.  The European and American herbaria had but little to offer in this regard.  Now I have been to Australia and am prepared to update my revision. Cultivated material at the Montgomery Foundation in Florida has been very helpful in understanding the living species.

     Several miscalculations attended my earlier efforts.  The proposal that a separate genus could be based on subterranean bulbous bases was rejected by Chen et al (2004, in Walters & Osborne, Cycad Classification) inasmuch as this character is not consistent with any other characters.  They also rejected the notion that a more restricted distinct genus, such as Dyerocycas Nakai (1943) could be recognized.  The emphasis on certain pinnae characters to support a subgenus (or section) also should be abandoned as no more than parallel development in clearly disparate groups.  There were also several misidentifications which require correction. 

     As a flood of new taxa materializes, each separate population tends to be looked upon as a new entity, not always supportable after careful examination.  Minor variations may merit specific recognition by some authors while others may feel that amalgamation would be more appropriate.  Thus, of the seventy some species named in the last decade and a half, less than a third will be recognized here.  That still leaves 55 total species, a considerable increase over the thirty seven recognized in 1998 (which included seven recent names).  A definite evolutionary sequence can be seen in this crowd of species.