The teddy-bear cholla is a cactus native to California, Arizona, and Nevada and northwestern Mexico.
The plant has a soft appearance due to its solid mass of very formidable spines that completely cover the stems. From a distance, the stems appear soft and fuzzy, giving it the name "teddy bear".
Hot temperatures pose special problems for cacti. Most leafy plants cool themselves during the day by opening their pores. The movement of water from stem to leaf to air keeps leaf temperatures from rising too high. Because their pores open only at night, cacti cannot take advantage of such transpirational cooling. They adapt to desert heat by internal mechanisms. Teddybear cholla, for instance, can withstand an air temperature of 138 degrees F. Most other plants would literally cook at this temperature, but teddybear cholla often rises 59 degrees F or more above the air temperature!