MAMMILLARIA WINTERAE

Excerpts from Jim Conrad's
Naturalist Newsletter

from the May 17, 2018 Newsletter with notes from a camping trip in the mountains east of Saltillo, Coahuila state, northeastern MÉXICO
MAMMILLARIA WINTERAE
During my recent camping trip in the highlands east of Saltillo, Coahuila, on April 5th I started out hiking on a valley floor, and climbed a small mountain that was grassy and scrubby at its base, but forested on top. Toward the top, at ±7000 feet in elevation (2100m), in openings on thin soil atop limestone rock and amid sparse forest of widely spaced pine and junipers, I found the little cactus shown below:

On this mountaintop the species was fairly common, with the body looking as if it consisted of many closely packed little green-chili-peppers, and it produced yellow flowers. Below, you can see its flowers closer up:

Spine disposition is an important feature in cactus identification, so a typical cluster of four, purple-tipped, whitish spines is shown below:

Such low-lying, spiny, ±ground-level heads can be a good adaptation, one worthy of unrelated species independently evolving the habit -- of undergoing "convergent evolution." In fact, just in Coahuila state five species in four different genera display such a habit, and are known by the Spanish name of Manca Caballo, meaning "horse crippler."

I know this because the excellent, well illustrated, Spanish-language Guía de Cactáceas del Estado de Coahuila by Alfredo Flores {was} freely available on the Internet. In that publication our Coahuila horse-cripper revealed itself to be ...

*UPDATE: In 2018 our cactus appeared to be Thelocactus rinconensis. However, In 2025, many more identification resources are available, and when this page's photos and information were uploaded to the iNaturalist website, user "tonymontes" recognized our cactus as MAMMILLARIA WINTERAE, and comparison with other identified pictures supported that ID.

Mammilaria winterae is endemic just to Mexico's Coahuila and San Luis Potosí states.