Tucson Mountain District Roads Closed Due to Flash Flooding
Several interior roads, including the scenic loop, are closed in Tucson Mountain District (west) due to severe storms and flash flooding on August 26th. Roads will remain closed until further notice. Check the park's facebook page for updated information More »
Labor Day Run - Rincon Mountain District Road Closure - Sept. 1st
Due to the Annual Labor Day Run, Saguaro National Park's Rincon Mountain District Loop Drive will be closed from 4:00am to approx 10:30am on Sept. 1, 2014. Please be advised of vehicle congestion along roadsides when approaching the park during this time. More »
Why saguaros have pleats
Because the majority of a saguaro is made up of water, an adult plant may weigh 6 tons or more. This tremendous weight is supported by a circular skeleton of inter-connected, woody ribs. The number of ribs inside the plant correspond to the number of pleats on the outside of the plant. As the saguaro grows, the ribs will occasionally fork and the corresponding pleat will also fork at the same place.
Sometimes saguaros have the chance to soak up a larger than usual amount of water - such as after a large summer rainstorm. The ground can become very soft after such a storm and with the added weight of the new water, the heavy cactus sometimes fall over or lose an arm.
Layers of a saguaro:
epidermis (green part)
cortex or pulp
ribs (with corresponding pleat on surface)
pith (inside the ribs)
Did You Know?
Gila monsters are one of two venomous lizards in the world. The other is the similar Mexican beaded lizard. Gila monster venom evolved as a defensive rather than offensive weapon.