Distribution: Habitat, distribution, and phenology: Populations of Hechtia schottii are found on karstic soils at the Maxcanu and Calcehtok caverns areas, both localities residing in the Sierra de Ticul, a small, low-elevation (max. ca. 200 m) mountain range oriented along a NW-SE axis in southwestern Yucatan State (Fig. 3). Here, the highest elevations in the State are found and Hechtia schottii grows in xerophytic shrublands, associated with Agave angustifolia Haw. Additional populations of the species are known from several localities in the Yucatan State (Sotuta, vic. Sisal, etc.) as well as in Campeche State (ca. Xpujil), where it grows in slightly more humid forests than those farther north. Close to the Calcehtok caverns there is a very large population of the species whose demography and phenology have been studied by our research group (Ramirez et al. 2000, 2008). However, due to the fact that Calcehtok and Maxcanu are close to a Mayan ruin (the Oxkintok Mazes), residents from the area frequently burn the vegetation of the place to reduce the amount of "spiny leaves" and keep the area "clean". The burnt plants are blackish, thus the common Mayan name for Hechtia schottii: "pool-boox" (pool:head; boox: black). Staminate plants of the species can be found blooming all year round, with a peak in April-May when also pistillate plants begin to bloom.