Ariocarpus Fissuratus
The Living Rock cactus is an unusual cactus in many ways. For one thing, it is the only member of its genus living in the U.S. It lives only in the Trans-Pecos. It has no spines. It is toxic. It is usually almost-to-completely invisible, making it difficult to find during any time of the year outside of its blooming period. It flowers only in the fall. It has a taproot. It was recently the subject of a major bust of cattle rustlers who were caught with over 5000 plants stored in plastic bags.
It is extremely slow-growing, and outside of the small area around the Big Bend National Park, and Big Bend Ranch State Park, it is rare, even in its home territory. The above photograph shows one of these plants as it normally appear throughout the year. I have sharpened this image to make it easier to see.
Here in West Texas the plant is round, and rarely even an inch tall. When dry, its taproot shrinks and pulls the plant down, often until it is completely covered. The pointed “leaves” are tubercles. Each tubercle has a groove that widens towards the base which is covered with dull-colored trichomes. This image illustrates the plant more plainly than the first image.
Flowers
Living Rock blooms from September to November. All flowers appear at the apex of the plant. They range from pink to magenta. Filaments are deep yellow with pale yellow to white styles and white stigma lobes.
Look for Living Rock cacti in rocky limestone or igneous soils. The plant does not tolerate gypsum well.
A ring of cactus thieves that stole over 5,000 of these plants was busted a few years ago. Thousands of these plant still live in the greenhouse at Sull Ross and are looking for homes. I’ve distributed over a hundred of them, but there are still many awaiting adoption. We hope that some may be returned to property owners from whom they were stolen in the first place!
aneyefortexas 
How much to buy/adopt one?
Are there any of these remaining at Sul Ross and if so how might I get one?
I’ve lost the details about the keeper of these plants at Sul Ross, but I’m pretty sure there are more. Her name is Karen Little and she manages the greenhouses for the Biology department. I looked her up on the web, but the info there is out of date. Perhaps you can get an email address or contact number from the college.
How can I adopt a few. Would like to try to transplant out at Terlingua Ranch.
I will have to check with Karen who operates the greenhouse at Sull Ross. I’ll let you know what I find out.
We have a thriving population of Living Rock cacti on our Terlingua Ranch property. These are some of our favorites and we’d love to know how might we adopt more.
I’ve really enjoyed your blog on the various cacti found in the Big Bend NP/SP area. Your blog pictures really help us as sometimes it is hard to identify what we’ve found.
One of our favorites is the fishook cactus, but they are exceptionally rare on our property.
I doubt they will do well here in the Hill Country – or I would adopt a few. I just saw one of these last month in the Cienega area of the State Park.
I doubt they will do well here in the Hill Country – or I adopt a few. I just saw one of these last month in the Cienega area of the State Park.