My trip to México took me to the small town of Zapotitlán Salinas. The town and nearby hills were once home to Popoloca people, and served as an important trading center. Then the main resource was salt, but today the town exists primarily for the onyx and marble mining industries. It is also surrounded now by the Tehuacán-Cuicatlán Biosphere Reserve. I learned that the reserve provides some protection for the landscape, but that low wages for local workers and the dominance of mining interests mean that the landscape is far from being sustainably managed.
Even with these concerns, it is a beautiful place to see columnar cacti. Coming from Arizona, I am accustomed to landscapes dominated only by saguaros. Here the desert was shared by several species, which seemed very saguaro-like from far away, but not on a closer inspection.
This first species is a tetetzo (Neobuxbaumia tetetzo), and was most common in lower areas. It grew tall and straight, and had a pale green color that harshly reflected the sunlight.
This second species is a cardón blanco (Cephalocereus columna-trajani), and was more common on higher-elevation slopes. It seemed more curved and soft, and would sway softly in the wind. The heads were covered in long white spines that seemed almost like a soft mat of hair.
This third species is a quiotilla (Escontria chiotilla), and was most common at lower elevation near dry riverbeds. It would grow into massive multi-armed structures, with a beautiful dark green skin.
And this fourth species is a trick – it is a saguaro (Carnegiea gigantea) growing hundreds of miles north, in Tucson!
Cacti have converged many times on the stem-succulent, columnar growth form. It seems to be a very effective way to live in dry desert-like conditions. But not all cacti do it – some of the most basal species in the family (Pereskia spp.) are small leafy plants inhabiting very different environments. You can learn more in this Edwards & Donoghue (2006) paper. Or by simply walking among the beautiful and heavily-exploited landscapes of Tehuacán…