The largest of the cacti family, the giant multi-armed saguaros and organ pipes look more like green telephone poles than a growing plant. Acknowledged as the de facto symbol of the Sonoran Desert, the saguaro, instead of proudly displaying its creamy white flowers for us to ooh! And aah! over, it decides to bloom only at night, which, unless you’re a bat with night vision you can’t see. But the saguaro isn’t just being cantankerous. It is just such nectar-feeding bats, and a specific kind of moth, that pollinate these giants of the cacti world.
At the other end of the scale, the fish hook cacti are among the tiniest. They grow to only about three inches tall and form lavender or pink flowers, about an inch at their widest that grow in a halo around the top of the cylinder-shaped plant.
The king of these cacti is the barrel cactus. When rain graces the barrel cactus’s home, it swells around the middle like I do after Thanksgiving dinner. The vertical ribs and pleated outer skin allow the barrel to expand like an accordion to absorb the precious moisture that maintains it until the next rain, which could be months away. Some large barrels grow to ten feet tall and have spines several inches in length. When they flower, they resemble a larger version of the fishhook, with a crown of pale yellowish flowers.
Most cacti, since they live in a land of sparse rainfall, have developed special methods of obtaining the moisture they need. The root systems, rather than sending down a long taproot seeking a water table, instead send out a network of shallow roots designed to capture at the surface what little rain falls before it evaporates. When the rain comes, the cacti sends out a system of tiny rootlets that soak up the moisture like a sponge and transport it to the cacti’s main moisture reservoir. When the precipitation disappears, the rootlets likewise disappear.
Next week in Cacti Part 3 I will look at the importance of cacti to the birds, lizards, and animals that make the desert their home, as well as how Native Americans used cacti in their daily lives.