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Abstract
Cycads of the Ceratozamia latifolia complex occur in the Sierra Madre Oriental in northern Veracruz and extend in range through eastern San Luis PotosÃ. Geographical features of the Aquismón district of San Luis Potosà include karst limestone hills and mountains ranging to over 1200m in elevation. Significant karst features are numerous in this area, and include large sinkholes and cave entrances up to 100m in diameter and, in some cases, of much greater depth. Certain of these features provide a well-defined niche for species of Ceratozamia, which are, in some instances, the dominant plant. The habitat is defined by zones with reduced or no rainfall and lower light intensities where the major forest species of the area are less prevalent. Zamia fischeri also occurs in this habitat, suggesting a commonality in environmental requirements and possibly also in pollinators and seed dispersal agents. The habitat provides a buffered environment where temperatures and humidity are moderated. This has implications for the extant plants as well as for the evolution of the endemic cycad flora.
