We encountered three species of cacti/succulents while in the Grand Canyon: Ferocactus acanthodes, Cylindropuntia whipplei, and Fouquieria splendens.
Ferocactus acanthodes, commonly known as California barrel or compass barrel cactus, are quite common in many areas of the Grand Canyon, including our landing location in the West Rim. The various subspecies spread across central and western Arizona, southeastern California and southwards into Baja California and Sonora, Mexico. As the photos suggest, they are generally found in rocky foothills or canyon walls and can grow quite large (up to 2m tall). The ones I saw were up to 1.4 feet tall at most.
Cylindropuntia whipplei, or whipple cholla, was more widespread in other valleys between the Grand Canyon and Las Vegas, but there were several specimens within view at our landing spot. It is a quite variable species depending on location and growing conditions. It also readily hybridizes with C. imbricata.
Fouquieria splendens, or ocotillo, was more common than I anticipated. Being the middle of summer, though, most were bone dry or had a few dried up leaves at the ends of their branches.
I will post more photos of these throughout the coming week - so if you want to see more, you will!