For the visitor, the best way to see the vegetation of this bioshere close-up is to visit the Helia Bravo Hollis Botanical Garden, located about 15 miles from Tehuacán. The garden is named after a Mexican botanist who catalogued the many species of cacti in the region. As you wander along the paths of the garden you will see 53 different species of cactus as well as agaves, yuccas and thorny desert shrubs.
Agaves (such as the species which are cultivated to produce tequila and mezcal) typically send up a tall flower spike and after flowering die.
Epiphytes or air plants grow on some of the thorny trees. They get their water from the early morning dew. In Mexico these plants are collected and sold to use as moss-like landscaping for Nativity scenes.
This unusual plant goes by the nickname of "elephant's foot". Supposedly if you place one hand on its trunk and the other hand exposed to the sun you will receive a burst of energy. Alejandro and I both tried it, and all we got was a hot palm.
There is much more to see in the biosphere... archaeological sites, rock formations, canyons and waterfalls. I would not mind returning to Tehuacán to see more of this little known but amazing reserve.