Living Rocks of Mexico

A Half Hour's Stroll To See Ariocarpus agavoides

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This article is reproduced form BCSS Journal Vol 20(2)2002, p76-79,. with the  kind permission of the Editor and Bill Weightman

Bill Weightman


20 Forest Way, St. Mary Cray, Orpington, Kent, BR5 2AQ, UK

Photos by the Author

Bill Weightman recounts a trip to see Ariocarpus agavoides in a remote region of the Mexican state of San Luis Potosi.

A special interest in the genus Ariocarpus has lurked in my broadly based love of the Family Cactaceae for more than fifty years and I have never passed up an opportunity to further it.  These plants tend to grow in inhospitable locations and, when in the field on several occasions, this has been a cause to reflect on my passion and to wonder if a transfer of attention to some more easily accessible group might make life more comfortable.

Ariocarpus agavoides was discovered by Ing. M. Castaneda and formally published in 1941.  Although right from the beginning it was recognized that the plant had strong affinities to the genus Ariocarpus it was originally considered to be sufficiently different to warrant a new genus of its own and it was published as Neogomesia agavoides - the generic name honouring Marte Gomez, at that time the governor of the state of Tamaulipas.  The specific name denotes its somewhat fanciful resemblance to a tiny Agave.  The plant was later transferred to the genus Ariocarpus by Anderson and there is no doubt that it belongs there.

The original site of discovery was close to the town of Tula in the state of Tamaulipas and until recently the few sites in that area were the only known habitats.  These sites are well known to cactus fanciers and they have been pillaged for years by unscrupulous collectors.  The plants are very well camouflaged and difficult to find but the local inhabitants are well aware of the interest that outsiders have in this plant and, for a few pesos, are very willing to take visitors to them.  The local woman who took my small party to see them in 1992 could not understand that we only wished to take photographs and not dig them up.  When we had finished photographing we paid her for her trouble and were walking away but I could not resist a glance over my shoulder.  She was busy digging them up doubtless in anticipation of the arrival of the next party of "gringos".  Although we may deplore this removal of plants we must remember that these Mexican country folk are poor and the selling of the local "weeds" to anybody willing to buy them is quite understandable.  The buyers, not the sellers are the real culprits.  In view of the mass removal of plants from the Tula area this species has long been on the list of endangered species although, perhaps surprisingly, they can still be found in the region.

It therefore comes as welcome news that two additional habitats for this plant have been discovered thanks to the efforts of Dr M. Sotomayor and his colleagues from the Sociedad Potosina de Cactologia in San Luis Potosi.  The two sites are in a very remote area of the state of San Luis Potosi and, in spring 2001 I was lucky enough to be able to visit one of them.

Our expedition consisted of two very well-filled four-wheel drive vehicles.  We set off together at 05.00 hrs but eventually separated one party to visit a habitat of Turbinicarpus flaviflorus and the other to try to locate the Ariocarpus.  I would dearly have liked to visit both sites but since it had to be one or the other I had no hesitation in choosing the Ariocarpus contingent.  Our party consisted of Jean-Marc Chalet, a Swiss cactus enthusiast who spends much time in Mexico, David Neville, John Pilbeam and myself.  We drove with some difficulty over appalling roads to a remote village that I have undertaken not to identify and there secured the services of an elderly local, Pedro, who claimed to be able to lead us to the plants.  Pedro was clearly a man of some standing in the village, proclaimed by the size of his moustache and his large silver belt buckle.  We set off, but the deep dry sand proved too much even for Jean-Marc's rugged vehicle and we were soon forced to abandon it.  "Half an hour's walk", Pedro assured us.  I should have known!  John Pilbeam, who has some walking problems, critically surveyed the surrounding countryside and elected to stay and guard the car and explore locally.  We remaining four set off.

The distance to the site turned out to be one and a half hour's walking and extremely tiring.  At every step we sank boot-deep into the powder-dry fine sand but the walk was not without interest.  Growing among the bushes of the sparse vegetation along the way were plants of Wilcoxia waldeisii, a species (or variety/form of W. poselgeri according to some taxonomists) reputed to have yellow flowers.  Pedro dug one up and, pointing to the tuberous root, indicated that it was "medicine", but for what precisely I could not determine.

My doubts about Pedro's capabilities as a guide proved to be unfounded. Although his ideas of time were rather different from ours he led us unerringly to the plants. They were growing on extremely dry, stony slopes and, once we had "got our eyes in" proved to be fairly plentiful.  A few plants of Ariocarpus retusus were growing on the same slopes. We admired the plants, took our photographs, rested a while and then set out on the tiring tramp back to our vehicle.  Having believed Pedro and his "half hour's walk" we had neglected the first rule of cactus hunting in Mexico and had carried no water with us.  It was with great relief that we eventually arrived back to find John Pilbeam comfortably asleep under a shady acacia tree and our car, with its cargo of drinking water, safe and secure.  Jean-Marc completed an exhausting but most satisfactory eighteen hour day by managing the long drive back to the city of San Luis Potosi without mishap.  The day will be added to the long catalogue of unforgettable cactus adventures that I have enjoyed in Mexico.

An interesting point regarding these San Luis Potosi plants is that they have small, often solitary, spines in the areole.  A feature of the genus Ariocarpus is that, except for rudimentary spines occasionally present in young seedlings, the areoles are spineless.  This is very difficult to capture photographically in a plant growing in habitat but is just visible in one of the accompanying illustrations.  The occasional presence of spines in the Tula plants has been recorded by Anderson but, in these (Tula) plants, it seems to be the exception rather than the rule.  This is clearly just a local feature not qualifying for taxonomic attention.


MARSHALL & BOCK (1941) Cactaceae 164: Genus 36. Neogomesia.

ANDERSON E.F. (1962)  American Journal of Botany. 49: 615.

ANDERSON E.F. (1965)  Cact. & Succ. J. (US) 37(2): 39-49.

FITZ MAURICE W.A. & BETTY  (1999) Cact. & Succ. J. (US) 71(5):211-212.

Illustrations (Will open in a new window)

  • Fig 1: Pedro, our guide on the expedition

  • Fig 2: Wilcoxia waldeisii - reported to be yellow flowered

  • Fig 3: Pedro explaining the medicinal uses of Wilcoxia waldeisii to David Neville (left) & Jean-Marc Chalet (right)

  • Fig 4: Ariocarpus agavoides showing spines in the areoles

  • Fig 5: Ariocarpus agavoides at the new locality

  • Fig 6: Ariocarpus agavoides blooming in cultivation

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