One the main motivations for a lot of my trips around Arizona and elsewhere the past few years has been my undying fascination with a very small, rare, often threatened, sometimes cryptic genus of cacti, Echinomastus. My Italian friend Bruno Magnani has a great website dedicated to these plants. The two of us wrote a couple of relatively exhaustive articles regarding the genus for Cactus & Co., the Italian's cactus society's journal, last year.
Recent revisions have folded Echinomastus into an expanded concept of the genus Sclerocactus. I respect this opinion and can definitely see the relationship, but I prefer to keep Echinomastus separate, mostly for geographic reasons. Regarding north/south distributions, Sclerocactus largely picks up where Echinomastus leaves off. The closest the two genera come to each other is probably in Death Valley, where a beautiful and delicate form of Echinomastus johnsonii grows not too far from a few dense populations of Sclerocactus polyancistrus.
Arizona is an Echinomastus hotspot. intertextus, erectocentrus, erectocentrus acunensis, johnsonii and arizonicus all occur within the state. Recent unpublished research by Marc Baker suggests a new taxonomy for most of the Arizona forms, making everything except intertextus a ssp. of erectocentrus, an east to west cline of increasing spine cover and a few other minor differences. I can definitely see this pattern (which roughly mimics the same east/west pattern of Sclerocactus ss), but I like to recognize detail and difference more simply, and I don't mind having a lot of names. I use subspecies and variety names here as species names, just for shorthand.
One of the population centers for the endangered Echinomastus erectocentrus (ss) is around Benson, AZ, along Interstate 10. A friend of mine says there is a population around Vail that is sympatric with intertextus, but I haven't visited there yet. Here are some photos from a trip I took in April 2010 down to the Benson area. There will be more photos from other Benson trips in the future also. I love southeast Arizona's habitat.
Hard to say for certain, but this could be a hybrid between versicolor (itself a hybrid?) and fulgida:
This could be Cylindropuntia X kelvinensis
I love the color of these Opuntia in this area, I guess violacea?
Big clump of one of my favorite geographical forms of Escobaria vivipara called 'bisbeeana':
Escobaria vivipara "bisbeeana' has great spines:
It is dry grasslands mixed with Sonoran Desert here, not sure what the technical term is, but like all transition zones, a lot of fun.
A pretty Opuntia macrorhiza, or maybe one of the colder weather forms of phaeacantha, either way a sure sign of some elevation gain and temperature drop:
Echinomastus erectocentrus in bud, near Benson.
Close up of buds:
I love the dramatic red spines of some forms of erectocentrus:
I was hoping to find plants in flower and was discouraged not to. But driving home, right along interstate 10, I noticed a great many in flower, whizzing by at 80 mph. Not the safest way to hunt cacti. There are a few incredibly dense populations of erectocentrus right along the highway, opportunistically taking advantage of the limestone road cuts. An example of habitat disruption actually leading to a strange rebound. Wish that would happen more often.
One of the repro strategies of erectocentrus and all Echinomastus (like Sclerocactus and Pediocactus) is a tendency to flower and set seed at a very young age.
Gives a sense of the density and robust health of these very small populations:
How odd to visit with these federally listed plants, on a high cliff right by the Interstate, with cars and trucks roaring by.