Living Rocks of Mexico
A Recent Field Trip in Search of Ariocarpus
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This article is reproduced form The Cactus and Succulent Journal (U.S.), Vol. 30 (1958). No .6, p171-174,. with the  kind permission of the Editor and Edward Anderson.



POMONA COLLEGE Claremont, California, Oct. 25, 1958  

This last summer an extensive trip was made to Texas and Mexico to look for and collect specimens of Ariocarpus. This journey was prompted by the necessity to see and learn the habits of these strange and interesting cacti in the field (Fig.1). The trip was actually only a part of a much larger research problem on the taxonomy of the genus Ariocarpus being conducted at Pomona College, Claremont, California, on a special Fellowship given by Dr. Gordon A. Alles of Pasadena. The provisions of this generous grant included two summer field trips to Texas and Mexico to gather ecological and geographical data, and to collect specimens for both the University of Mexico and Pomona College. Part of the summer of 1957 was spent in the field in Texas and Mexico in preparation for a more extensive trip which was taken this year.

Many questions were found to be unanswered after a careful study of herbarium specimens and literature had been completed. It was felt that only careful field studies and extensive collections could tell the answer to such questions as why there have been forty-one different taxonomic names proposed for probable plants of this genus, and more specifically which of the names are valid. Two other questions it was hoped would be answered by the field trips; what is the exact geographical range of each species, and is the proposed genus Roseocactus valid? To facilitate matters for the preliminary research and for purposes of collecting in the field, the proposed genus Roseocactus was considered as part of the genus Ariocarpus. Determining the validity of Roseocactus is a goal of the present research.

The expedition consisted of only one vehicle, a 1958 Ford pick-up truck with a canopy for storing equipment and specimens. David Sands of Glendale, Arizona, assisted during the trip as a research assistant. The actual collecting began in the Big Bend region of Texas where numerous localities had been listed by Dr. Lyman Benson of Pomona College and Dr. Norman H. Boke of the University of Oklahoma. Between Alpine and the park boundary (Fig.2) were found areas where there were literally thousands of Ariocarpus fissuratus (Fig.3).,the "living rock" or "star cactus." Common plants encountered with it on the low lime-stone hills were Larrea divaricata, Agave lecheguilla, Yucca sp., Ephedra nevadensis var. aspera, Dasilyrion wheeleri, Koeberlinia spinosa, and Fouquieria splendens. There were also many cacti in the area such as Opuntia engelmannii, Mammillaria lasiacantha, and Echinocereus pectinatus. Near the Lajitas junction just outside the park entrance were such cacti as Echinocactus horizonthalonius, Mammillaria sp., Echinocereus stramineus, and Opuntia sp., on the flatter ground, and on the limestone hills were specimens of A. fissuratus, Echinocereus pectinatus, and the interesting yellowish variety of Epithelantha micromeris. Numerous localities were found within the park such as south of the park headquarters, on the road to San Vicente, on the hills near Tornillo Creek, and on the hills a little toward Boquillas Canyon. However, these localities were limited only to collectors with permits. Cacti growing with the Ariocarpus in these localities were Coryphantha tuberculosa, Echinocactus horizonthalonius, Echinocereus pectinatus, Echinocereus stramineus, Epithelantha micromeris, Mammillaria lasiacantha, and Opuntia sp. North of the park boundary on the road to Marathon is another good location where numerous specimens of A. fissuratus were collected. The final collecting point in Texas was near the easternmost limit of the "living rock" which is the Pecos River. It was collected west of the town of Langtry.

Upon crossing the border into Mexico, interest was directed to the beautiful city of Saltillo, Coahuila, around which were numerous localities for collecting Ariocarpus retusus. One of the best collecting areas was on the unpaved road south of Saltillo. on the way to Concepción del Oro near Carneros Pass (Fig. 4). There were many fine specimens of A. retusus (Fig.5, Fig.6) and the proposed species A. furfuraceus (its type locality). In this locality were such plants as Larrea divaricata, three species of Agave, Mimosa monancistra, and several different species of Opuntia. In this area of Mexico Ariocarpus is called "chaute" or "chautle" by the natives and is reported to be sold on the market for medicinal purposes. East of Saltillo on the new superhighway other large and beautiful specimens of Ariocarpus retusus were found.

Parras, Coahuila, was the next destination in the trip, and here were found some beautiful specimens of Ariocarpus fissuratus var. lloydii (Fig.7)  which is often more robust and lacks the lateral fissures when compared with its Texas counterpart. The locality, recommended by Mrs. Dennis Cowper of Belen, New Mexico, had some specimens which measured 25cm. in diameter and 20cm. high. Only Neolloydia and Opuntia were found with the Ariocarpus, but nearby were some fine specimens of Echinocactus horizonthalonius with black spines. Another reported location of this variety of Ariocarpus is in the vicinity of Concepción del Oro at Hacienda de Cedros, the type locality. However, poor roads made this area impossible to reach.

Near the small village of El Huizache (Fig.8)  south of Matehuala were found some of the most interesting and baffling specimens of Ariocarpus of the entire trip (Fig.9).. These plants had characters unique to only A. retusus and characters unique to only A. trigonus, and they did not fit any previous descriptions. Some people say they are A. retusus, but comparison with the type picture made by Scheidweiler in 1838 shows that they are definitely not the same. Because of the fact that the locality is intermediate between areas where A. retusus and A. trigonus are found, and because they have many features of each species, it may be that this is a hybrid population. However, only tentative conclusions can be drawn about this at present, and much more study will have to be done. This general area of Mexico was one of the richest in cacti that was found, and had been recommended by the late Howard Gates of Corona, California. Some of the cacti recognized were Echinocereus pectinatus, Echinocactus grusonii, Ferocactus pringlei, Astrophytum myriostigma, Lemaireocereus sp., Opuntia spp., Lophophora williamsii, and Mammillaria spp. Many of the names were not known, and consequently could not be listed.

The locality at which Ariocarpus kotschoubeyanus (Fig.10) was collected had been graciously described by Sr. Jerzy Rzedowski of the Universidad Autonoma de San Luis PotosI. It was only a short distance from the area near El Huizache, but only Lophophora williamsii, Opuntia sp., and Echinocereus sp. were found with it. Another locality in the state of Queretaro had been described by the cactus nurseryman Willi Wagner, but it was impossible to reach because of damage caused by recent floods. Scheidweiler described the original species of Ariocarpus as coming from the area around San Luis Potosi, and here east of the city on the highway to Rio Verde were found numerous specimens. However, many plants had been mutilated, apparently by goats. Many different types of cacti were growing in this same area such as Mammillaria, Neolloydia, Ferocactus, and Opuntia.

The search for Ariocarpus was briefly interrupted with a visit to the cactus garden and nursery "La Quinta - F Schmoll" now run by Willi Wagner at Cadereyta des Montes, Queretaro. The road then led to Mexico City where problems connected with the study were discussed with Dudley Gold and Dr. Helia Bravo. Invitations were extended to attend the monthly meeting of the Mexican Cactus and Succulent Society, and the evening proved to be very interesting and enjoyable. Dr. Eizi Matuda was also able to obtain permits to export the specimens that had been collected.

The return trip included only one area for the collecting of Ariocarpus, and this was southwest of Ciudad Victoria on the very difficult and badly weathered road to Jaumave in the state of Tamaulipas. Here many beautiful specimens of Ariocarpus trigonus (Fig.11) were collected and photographed along with Astrophytum myriostigma. Here the Astrophytum were surprisingly globose. Within the same area were species of Echinocactus, Hamatocactus, Mammillaria, and Opuntia. If the roads had been better a great deal more time would have been spent collecting in this interesting and comparatively unexplored valley of Jaumave.

With the completion of the field trip, the search for Ariocarpus ended for the year, but now it is necessary to study the data and the specimens in the hope that a clearer picture of this fascinating and important genus can be drawn.

  The quality of some of the illustrations accompanying this article, does not meet with today's more exacting standards. This is a consequence of the reproduction technology of the time,  

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