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!
Did You Know?
One of the most beautiful spectacles in spring is the creamy-white blossoms of Joshua trees. These white candles can be seen from February to late March. Joshua trees do not branch until after they bloom, and they don’t bloom every year.
more...