I still vividly remember the first time I saw Ariocarpus in the field. My wife and I had driven to the Big Bend region of Texas in the summer of 1957, on our way to Mexico to search for and collect Ariocarpus and peyote (Lophophora williamsii). I needed specimens so that I could begin my graduate research on these plants at the Rancho Santa Ana Botanic Garden under the direction of Dr. Lyman Benson. I was interested in studying both peyote and Ariocarpus because both had been included in the genus Anhalonium in the 19th century, suggesting that they might be closely related. My research determined that they are distinct genera (Anderson, 1964, 1969).

We walked up a low limestone hill, sweating in the hot August sun, looking for Ariocarpus fissuratus (Fig 1). As we neared the top of the hill I saw a strange pattern in the limestone rock. I stooped and immediately recognized it as the famous "living rock" cactus. I called to my wife, who hurried over to examine one of the strangest of all cacti. Over the next several weeks we learned to search for a variety of cacti, but none proved more difficult to find than Ariocarpus.

As I think back over the more than 40 years that I have studied Ariocarpus and the hundreds of plants that I have seen in their natural habitats, three instances come to mind concerning their amazing "ability" to hide from the searcher. Two years later, in 1959, my wife and I (Fig 2) returned to Mexico to collect more research materials. This time we drove over a terrible road to the town of Tula, Tamaulipas. In fact, the road was so bad (Fig 3) that everyone had simply driven to the side of the road, making a track through the brush. We were seeking the elusive Neogomesia agavoides, which had been described several years earlier by Marcelino Castaneda (Fig 4), an engineer who had explored extensively in the state of Tamaulipas. He also discovered Obregonia in the Valley of Jaumave.

We had been told that it would be impossible to find Neogomesia when not in flower, as they were so well hidden. Time slowly passed in our search, and we began to believe that we were not going to be successful, but suddenly I saw a few tiny tubercles projecting out of the rocky soil (Fig 5). I kneeled and saw that it was a Neogomesia! As we had wandered over the hill in our search, several curious children from the nearby town had come to watch us. We asked them to help us find a few more of these little plants, which they called "dulces" because they sometimes ate them for their sweetish taste. Eagerly they began to crawl among the shrubs, and soon their sharp eyes found enough plants for my studies. These specimens ultimately showed that Neogomesia, in fact, belonged in Ariocarpus (Anderson, 1962).

One of the most humorous searches I had for Ariocarpus was for A. kotschoubeyanus (Fig 6, Fig.7). I had located this species at several localities in the state of San Luis Potosi, but my travel companion of many expeditions, the late Richard 0. Albert, had found a population of A. kotschoubeyanus with white flowers in Tamaulipas. He wrote me a letter, giving me detailed instructions on how to find the site on the trip I was planning the following month I went to the silt plain he had described and over the next several hours searched in vain for the plants.

The following year Richard joined me on a trip to Mexico, and we returned to this site where the "kotschies" were supposed to be. We walked on to the silt plain, and I told him that this was exactly where I had come the year before but had not found any. He laughed, pointed at my feet, and said, "You are standing on them!" I looked down, refocused my eyes, and suddenly saw a pattern in the silt. Then another...and another He was right! In a few minutes we had found literally hundreds of these tiny cacti, nearly hidden in the silt. One needs to look for the patterns, adjust his mind-set, and there they are.

One would think that my many years of experience would have helped me spot these elusive cacti, but in 1995 I again experienced the frustration of not being able to find the Ariocarpus plants that I knew were there! "Fitz" Fitz Maurice and I had gone to a site of Ariocarpus bravoanus ssp. hintonii (Fig 8, Fig 9, Fig 10), which we had set up for long-term monitoring. We found several plants and noted that they were in good condition, not having been disturbed by any human activities. We then went to Matehuala to meet George Hinton, who had actually discovered the plants at the site we had just visited. Later that day we returned with George to exactly the same area where we had seen many plants that morning. In the different light of the afternoon the plants were invisible! We searched for more than an hour, locating only eight, where we had seen dozens that morning. Again, we had learned that these plants may be nearly impossible to find at one time of day, but no problem at another.

My studies of Ariocarpus for nearly half a century have given me many fond memories, but some I would just as soon forget. The first time we went into the Valley of Jaumave was in 1958, and we literally crawled along a riverbed and up steep hillsides to reach the valley and Ariocarpus trigonus It was one of the most harrowing experiences of my life! Now the same area is reached by a splendid paved highway. Once we got into the valley, we found many beautiful populations of this species (Fig 11), which we have now concluded is a subspecies of Ariocarpus retusus (Anderson and Fitz Maurice, 1997). Unfortunately, in recent years we have seen large areas of the Valley of Jaumave transformed into agricultural fields, and many native plants have been lost Ironically, some of the fields are planted to Aloe vera, another succulent.

In the late 1950s I was told that A. trigonus grew north of Monterrey, a considerable distance from the Valley of Jaumave, so we went there to look for it. After some searching, we found it, thus extending its natural distribution by many kilometers and confirming that probably this was the locality where the plant was first discovered. However, recently I returned to the area and was disappointed to see that urban sprawl and agriculture have destroyed the habitat.

I was much honored when Hector Hernãndez of the Universidad Nacional Autónoma de Mexico (UNAM) asked me to help describe a new species of Ariocarpus he had discovered. Hector told me that one day he had been collecting cacti in the state of San Luis Potosi and had been surprised that when he dug up a fairly large cactus he found a smaller one in the pile of dirt the new Ariocarpus! We subsequently described this plant as A. bravoanus (Figs.12, Fig 13), honoring our dear friend and colleague, Dra Helia Bravo (Hernández and Anderson, 1992). I have visited the site of A. bravoanus several times since we described it, and in 1993 we set up a permanent monitoring plot to study the plant and its dynamics. However on the second year of our research we noted holes in the area, where someone had collected some plants. The following year we found many additional holes, and more recently collectors have even dug up specimens from the marked plots, simply tossing the tiny metal tags to the side. I was not only depressed at the flagrant illegal collecting but angry that these individuals would not even respect an obvious scientific study plot. In the last few years this site has been terribly devastated by illegal collecting.

In 1986 I was a member of a team of scientists under the leadership of the late Hernando Sanchez Mejorada studying the rare cacti of Mexico for World Wildlife Fund. We visited the area near Tula, where Ariocarpus agavoides occurs, having heard that continued illegal collecting had nearly wiped out the species at the only known locality. Our investigations were not encouraging, for we discovered that, indeed, widespread collecting was occurring despite strict Mexican laws prohibiting it. Moreover, we also learned that erosion was destroying large areas of habitat. This was due to overgrazing and the construction of the highway that now bypasses the city. Our report to WWF was pessimistic on the future of this species. I have returned to Tula several times since the WWF study, and we have found that, remarkably, there are still many plants of A. agavoides and that in many sites it continues to thrive. In fact, at one location near the town we set up a plot of one square meter and counted more than 100 plants in it. However, urban sprawl, as well as illegal collecting, continue to seriously threaten this species. Happily, another site for A. agavoides has been found at some distance from Tula. I believe the long-term prognosis for this species is fairly good.

I recounted my adventure in reaching the Valley of Jaumave in 1959. Three years later I needed to go to the Valley of Rayones to study Ariocarpus scaphirostris. In those days there was no real road into the valley, one simply had to ford the river (Fig 14) and proceed along a 4-wheel drive track. I did not have such a vehicle, so arranged for someone to take me from Montemorelos. We met at the appointed time and headed into the mountains in a Jeep station-wagon. When we reached the river, the driver stopped, muttered to himself, and got out. He was a bit disturbed, for the month was January and by this time of year the river should have had little water. Unfortunately, it had a lot of water, but he did not let this stop us. He located some plastic bags and rubber bands, and proceeded to wrap each spark plug and the distributor as a water-proofing system. In a few minutes we were off again, splashing through the river 39 times, with the water coming under the doors 14 times. We successfully reached our destination late in the day, set up camp, and eagerly looked forward to the next day and our search, not only for A. scaphirostris (Fig.15, Fig 16), but also Aztekium ritteri. Our search was successful, but again we learned how elusive Ariocarpus can be. We crawled on our hands and knees over the flaky limestone chips, looking for tiny tubercles protruding out of the soil, eventually locating several plants for my research. In subsequent years I have returned to this interesting valley, and I am optimistic that A. scaphirostris will survive. I have recently been told that another population of this species has been discovered, far from the Valley of Rayones.

Throughout my studies of Ariocarpus, I have been fascinated by the variations of some of the species, especially A. retusus (Fig.17). It is particularly interesting to note the gradual change of tubercle shape as one goes from north to south through the species' range. Ariocarpus retusus is the type species of the genus, so I decided that it was important to try to locate the possible site from which Henri Galeotti may have first collected this plant in the 1830s. I studied the literature and found that he travelled extensively out of the city of San Luis Potosi, so I decided to begin there. Early maps and accounts also showed typical routes of travel, one of the most common being directly to the east. We therefore headed east ourselves, stopping at likely looking hills to see if we could locate A. retusus. We were fortunate, for only about 10 miles east of the city limits we found it. I then compared these plants with the one illustrated by M.J.F. Scheidweiler in his 1838 description. They matched remarkably well, so I was able to designate a plant from this locality as the neotype (Anderson, 1964).

Over the years I have rarely had difficulty in determining which species of Ariocarpus I was examining, and this included both A. retusus and A. trigonus. However, Charlie Glass and "Fitz" Fitz Maurice stumped me. They took me to a population of Ariocarpus (Fig.18) near Aramberri, Nuevo Leon, and asked me what species it was. I looked at many plants, first thinking one way, then another. They then shocked me by saying that many of these plants produce red flowers, unheard of in any known Ariocarpus species. For the next several years we carefully studied these plants, and we decided that it was a likely hybrid population between the "typical" A. retusus and A. trigonus. We have now published our conclusions (Anderson and Fitz Maurice, 1997), some people have disagreed and even suggested other alternatives. This simply proves that many questions are still not answered so far as Ariocarpus is concerned.

Controversy-and disagreement-are often part of scientific investigation. Many botanists and I may have added to this controversy, but, hopefully, we have also clarified many things as well. No one has all the answers, nor will all the questions ever be answered I hope that my research on Ariocarpus has been of value to some; it has stimulated discussion, to say the least. I look forward to the future and the opportunity to further study Ariocarpus and the many other amazing species of cacti.

References

Anderson, E.F. 1962. A revision of Ariocarpus (Cactaceae) II. The status of the proposed genus Neogomesia. Amer. J. Bot. 49(6):615-622.

Anderson, E. F.  1964. A revision of Ariocarpus (Cactaceae) IV. Formal taxonomy of the subgenus Ariocarpus. Amer. J. Bot. 51(2):144-151.

Anderson, E. F. 1969. The biogeography, ecology, and taxonomy of Lophophora (Cactaceae) Brittonia 21(4):299-310.

Anderson, E. F. and W.A. Fitz Maurice. 1997. Ariocarpus revisited. Haseltonia 5:1-20.

Hernandez, H.H., and Anderson, E. F. 1992. A new species of Ariocarpus (Cactaceae). Bradleya10:1-4.