About 850 spp. of phanerogams and cryptogams are listed. There are brief discussions of geology, climate, agriculture, and relationships of flora to those of other parts of Mexico. A detailed account of the vegetation recognizes 4 regions and 11 subdivisions. An attempt is made to correlate these zones with similar zones described by other authors for other parts of Mexico. The list includes: Porotrichum leavenworthii E. B. Bartram, Pancratium leavenworthii Standley and Steyermark, Manihot mobilis Standl., M. tomatophylla Standl., Phyllanthus perpusillus Standl., Diospyros martinezi-ana Standl., Thevetia peruviana var. pinifolia Standl. and Steyerm., Pectis imitans Standl., and P. leavenworthii Standl.