Geohintonia mexicana (2010)

By Eric Driskill (March 2010)

Geohintonia mexicana belongs to the tribe Cacteae and the subfamily Cactoideae. This Mexican genus is monotypic, having only one species in the genus.

Some believe this plant to have originated from an ancient hybrid, possibly between Aztekium hintonii and Echinocactus horizonthalonius. G. mexicana grows alongside A. hintonii on gypsum cliffs and hillsides of the Sierra Madre Oriental in Nuevo Leon, Mexico.

E. horizonthalonius has two varieties: nicholii and horizonthalonius. E. horizonthalonius var. horizonthalonius occurs in the Chihuahuan Desert to San Luis Potosi. With G. mexicana growing alongside A. hintonii and E. horizonthalonius var. horizonthalonius growing through that area and continuing almost another 200 miles further south, it is possible that it is a hybrid between the two.

G. mexicana and A. hintonii were both discovered by and named to honor George Hinton. Hinton discovered A. hintonii in 1990 and G. mexicana in 1991. He asked his friends Charles Glass and W. A. Fritz Maurice to describe both finds.

Soon after announcement of the discovery of G. mexicana, some collectors, excited about a new genus of cacti, sought specimens, often illegally, and the population came close to becoming extinct in the wild. Only the future will tell what population reduction in the wild will do to the long-term fate of this plant.

The blue-green plants are solitary and globose, and at times become columnar. Ribs are well defined from 18 to 20 and lack tubercles. Plants grow to 4.5 inches tall and 4 inches in diameter. Areoles extend along the rib edges. Spines, which are 0.3 to 0.5 inches long, are slightly curved and shed easily. Flowers are pink to magenta and open during the day.

Despite being very slow to grow, the plants are relatively easy to grow. You should provide a well-draining soil. G. mexicana require strong sun and light watering to maintain compact growth.

The plants can be grown from seed, but take a decade or more to reach flowering size. You will, of course, also see grafted plants attain flowering size in a fraction of the time, although in a few years they grow so large as to be hard to recognize, since we are used to seeing even old plants in small pots and taking their time. It may be possible to graft plants for a time and then root them separately to obtain larger plants.

Whatever you do, make sure not to buy a plant that appears to have been field collected. You may have to enjoy a smaller seed-grown plant for a few years, but you will know you aren’t contributing to the disappearance of this beautiful plant from its native gypsum perch.