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Excerpts from Jim Conrad's
Naturalist Newsletter
entry dated May 18, 2022, notes from a camping trip among hills about 7kms ENE of Tequisquiapan, Querétaro state, MÉXICO
elevation about 2020m (6600 ft), near N20.57°, W99.85°
"BIZNAGA" CACTUS
Beneath an isolated, late-dry-season leafless oak tree on rocky, grassy slopes, the above small cactus bristled with thick-based, hard spines bent close to the cactus's body. Especially noteworthy was the curiously wavy ribs.
Several years ago, also here in Querétaro state, I'd seen a ball-shaped cactus with such wavy ribs, but that cactus's spines were longer and more slender, and its ribs not so wavy. It was Stenocactus lamellosus, known locally as Biznaga. However people use that name Biznaga for any ball- or barrel-shaped cactus, no matter whether its body has ribs or nipples like the mammilarias, or what the spines look like. Still, often that's the only name to be found.
In our area, if a ball- or barrel-shaped cactus displays many thin, ondulating ribs, you can bet that it's the genus Stenocactus, and that people will call it Biznaga. In our part of the arid, central Mexican uplands known as the Bajío, seven Stenocactus species are known. And here, if you have a Stenocactus with ribs as slender and extremely wavy as this one's, it's STENOCACTUS OBVALLATUS, of course known as Biznaga.
Stenocactus obvallatus, like the Stenocactus lamellosus mentioned above, is a member of the "Stenocactus crispus Complex," and similarly is endemic just to parts of the arid, central Mexican upland states of San Luis Potosí, Guanajuato, Hidalgo, and here in Querétaro. A good guess is that thousands of years ago the species Stenocactus crispus covered a larger area, but with time evolved several geographic variations adapted to their local environments. At first these variations would have been considered subspecies of Stenocactus crispus, but now at least the last expert to study the matter considers the local population to have evolved to the point that it's a full species, Stenocactus obvallatus.
It's a special pleasure to encounter such species, for this entire region is plagued by cactus robbers who sell them to gardeners and collectors, including wholesellers in cities. I'm constantly finding holes dug in isolated places, clearly for the removal cacti, often with damaged, unsellable parts of the removed cacti seen lying next to the hole. It won't be long until all such cacti are extirpated from vast areas, even made extinct.