We had a day sightseeing in Big Bend. Unlike last year, when we hunted down some 6 GPS locations and found the plants expected at these stops, this time we went to tourists spots such as an overlook and a canyon in the Rio Grande and watched people walk through the water from Mexico and the US. Stop numbers are S2252 (scenery), S2253, at the northern entrance to the park, coming from Marathon, S2254 at the Fossil Bone Exhibit, S2255 at the Rio Grande Overlook and S2256 at the Boquillas Canyon Trail. We asked at two of the visitor’s centres to see the local cactus experts. As usual they were out elsewhere. At one of the centres, a nice lady, who was on leave from her regular job as a warden at a Park in Alaska, tried to remember what she had been taught when she joined, which took us to the Rio Grande Overlook where we failed to see Epithelantha and Lophophora, but we had seen plenty of those elsewhere last year.
Tomorrow we cross into Mexico
And of course we looked around for cacti and found Echincereus engelmannii, E. dasyacanthus, lots of Cylindropuntia and Opuntia sp., Escobaria tuberculosa, Mammillaria pottsii and Ariocarpus fissuaratus – some dozen plants before we got fed up with taking their picture.
The most interesting information gained today came from a geology book (too heavy to bring back to the UK, and a cactus book that I bought here last year – but of course left back at home in the UK. Echinocereus viridiflorus ssp davisii and Coryphantha nellii are said to occur near Marathon and we were driving backwards and forwards along US Highway 385 from and to the town. The cactus book told us to look along the 385, around c 10 miles south of Marathon where it has a very restricted distribution growing on novaculite. The geology book told us that south of Marathon novaculite occurs folded so as to form horseshoe shaped layers, similar in shape to those that we saw in NW Argentina. The map told us that we were driving along the Caballos Mountains, with geological structures as described. Caballos is Spanish for Horseshoes. Stories picked up back home in the UK suggest that the plants grow on private property with owners who do not take kindly to visitors on their property. I am glad to know where to look on a future occasion and to try to contact the owners by email in advance for a future visit.