Just outside of Tucson is the Saguaro Forest. The Forest was once almost impassable because of the thick and thorny foliage (if cactuses can be called foliage). Due to a hard frost in the sixties and another one in the eighties many of the cactuses died, leaving the forest terribly thinned. It is only now starting to recover. Saguaros grow slowly taking 75 years to start growing sidearms they can live for over 150 years. In contrast their spines can grow up to a millimeter per day. They will physically change appearance when it rains as they soak up the moisture to process and use it later. Truly unusual plants.
It’s often surprising to me the means that plants and wildlife develop to live in such harsh parts of the world.