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travelog 45
In Search for Plants - Pachyphytum
The genus Pachyphytum has fascinated us for a long time because these plants not only look exceptional but also produce unusually beautiful inflorescences. There are four species of this small genus in the Mexican states of San Luis Potosi and Guanajuato, and we're going to look for them.
We hope that we have awakened an interest in this attractive plant genus in some of you. Most of them are easy to take care off also in horticulture and they will flower every year with the right attention. You only have to remember that they are not frost-hardy.
The longer we travel the more we're convinced that we made the right choice with what we're doing. Obviously, it is a lot of fun to chug through isolated areas (and to explore them also by foot) and to look out for botanical specialties. That we can discover forms of plants that represent the transition between two species, makes the whole thing even more interesting. Nature out here is rarely as easy as it is sometimes presented in books. But as is well known, this is not only valid for the plant kingdom...
February 2002
Julia Etter & Martin Kristen
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Pachyphytum hookeri: According to the scientific literature we have, this plant is known only from six localities, among others from a canyon near Ahualulco in the state of San Luis Potosi. For two days we search for the pachyphytum, in vain. Instead of this we accidentally find Echeveria agavoides which only grows in the steepest vertical cliffs because, if not, this plant would be eaten mercilessly by hungry goats and burros. 
Also Graptopetalum pachyphyllum and Sedum greggii, which belong to the same big plant family, the stone crops (Crassulaceae), grow in this canyon together with agaves and cacti. Without the little ranchos built around the scarce water supply, this place would certainly be paradise. But with the ranchos come all the goats and Peter, the goatherd, with Heidi, searching for the best pastures for their animals. Not even the highest mountains are safe from the voracious animals which are such outstanding climbers. Nevertheless we make a find just a little bit further south. The cliffs at the Puente Tecolote are covered with little plants, all of them with short inflorescences and orange-red flowers. At the locality for Mammillaria schwarzii which will not be named because there were already enough collectors up to mischief here, practically wiping out those little beautiful cacti at their natural location, we make a find as well. We go on a field trip with our host in San Luis Potosi, W. A. Fitz Maurice, where he shows us Mammillaria schwarzii. In addition we find the flowering pachyphytum in the cliffs, almost more interesting to us than the rare mammillaria. The rocks are covered with clusters of plants. Their flowers are visited by hummingbirds.
Pachyphytum oviferum: The locality information is more than questionable for Pachyphytum oviferum. There are several places in the state with the same name, and even more names which we can't find on any map, or which were changed by the local people in the meantime. Finally we get the crucial tip and set off to the lowlands (+/-3000 feet) of San Luis Potosi. The temperatures are already very high, the wind is hot but it at least drives away the tiresome little flies. If you once find the right area, everybody knows about the "Cajon del Rio". But they say that we will never be able to reach it with our truck, we would have to walk for at least an hour. As proud Swiss people, we don't mind that at all... Nevertheless we want to try to drive as close as possible to the plants because we don't like to hike long distances in such high temperatures. The dirt road always runs along a dry river valley that meanders through the mountains. From time to time we pass an abandoned rancho. Some of them only look abandoned but a beautiful flower-garden, a cultivated corn field or some curious children who peer through a fence, put us right. Soon we have several tracks in the dry riverbed. Then, suddenly, all the tracks disappear somewhere in the sand where soon enough there's no getting further, even for us. 
We're happy to get through the deep sand (why, after all, do we own a Unimog?!) and to finally reach firm ground where we "safely" (no thunderstorm clouds in sight...) park in the rocky riverbed. We only have to walk 15 minutes along the river until we reach a narrow part of the canyon where huge boulders lie on the canyon floor. Clusters of Pachyphytum oviferum hang from the vertical cliffs! All of them are in full flower. The only problem is getting close enough to the plants to take good pictures. There is still some water in this canyon and in the little pools live newts and frogs. Birds are singing in the trees and tillandsias and bromelias adorn the rocks. It's a beautiful place which apparently a while ago was to have become victim of a little dam. Shafts and ladders still give evidence of that. Fortunately this project, as so many more in Mexico, fizzled out and the money drained away.
Pachyphytum kimnachii: Since it's getting too hot in the lowlands, we want to get off into the mountains. For that, Pachyphytum kimnachii is perfect because it grows at about 5400 feet. From Rio Verde we take a very narrow road that spirals upwards into the mountains. After we meet a Coca Cola truck and a public bus we know that there is a way through for us too. This mountainous landscape is beautiful. Mountain ranges change with deep canyons, columnar cacti inhabit the slopes and further up you can even find pine and oak trees and violets on the forest floor. Sometimes thick clouds come up from the Gulf of Mexico, they unload all their moisture on the cliffs above us. The trees are adorned with long tillandsia-beards (Tillandsia usneoides) which give the landscape an almost eerie appearance. First of all we climb up to the cliffs above the road with the sweat of our brow but we can't find the plants at the mentioned position. Instead we find flowering colonies of the cute little Sedum reptans and two species of villadia which cover the mossy rocks. 
The bark of the oak trees is not only popular with the tillandsias. Little orchids, ferns, echeverias and even cacti have colonized this secure height (not even goats climb that high). That's why you not only have to direct your eyes to the ground but you also have to examine the trunks and thicker branches where you can find interesting plants too. Disappointed, we want to give up our search for Pachyphytum kimnachii, when we find those huge plants (which we expected to be a lot smaller) in big colonies just around the corner, a little bit below the road. They are in full flower and the cream-colored, arching inflorescences glow and sway in the wind. Especially against the light they form conspicuous wave patterns that flow over the dark rocks. We're very fascinated and decide to stay for another two nights to have enough time to document the plants thoroughly. A little bit further on in the lowlands, in the many canyons, in the land of the fluoride mines, somewhere between the states of San Luis Potosi and Guanajuato, you can also find other interesting plants. Fantastic columnar cacti, covered with fragrant flowers, tree-like myrtillocacti, huge ferocacti, and to our surprise even Astrophytum ornatum with yellow flowers, a plant which is originally described only from other Mexican states.
Pachyphytum fittkaui: From the scientific literature we know several localities for this fourth pachyphytum which we want to visit on our tour of the mountains southeast of the capital of San Luis Potosi. The first locality is at the km-marker 16 measured from a certain city. We stop there, firmly convinced that the km-markers on our road are measured from this very city. We find some plants in the rocks above the road but we are surprised that there aren't more around. Soon we realize where the mistake lies: we're at the wrong place! 
At the correct type locality we clamber up through the thorny brush, but still we can't find many more plants. That's why we drive to another locality, on a road that can be used in some places only as a cow track. Once again we're happy to have a Unimog. And... we find a fantastic locality on a river which is at this time of the year very dry apart from some muddy puddles. It's an ideal camping spot under some shade giving trees. The west-oriented cliffs are little gardens with agaves and hechtias, moss, different ferns, huge bromelias and tillandsias, and of course "our" much sought-after plants: Pachyphytum fittkaui. Besides that there grow also Echeveria agavoides, Sedum palmeri, and several cacti. The many flowers are not only visited by hummingbirds and fat bumble-bees, they are also very popular with huge colorful butterflies, monarchs, swallow-tails, brimstone butterflies, and many more. For two days we don't see a living soul, let alone traffic. It's a very peaceful place until a cow herd comes by and the hungry beasts eat off all the beautiful inflorescences within their reach. We leave this little paradise which is only so unspoiled because it is so hard to reach in a car.