Thanks to its unique crossroads locale, the monument is home to a wide range of specialized plants and animals, including its namesake.
This stretch of desert marks the northern range of the organ pipe cactus, a rare species in the U.S. With its multiple stems, the cactus resembles an old-fashioned pipe organ—you can almost hear them serenading the desert.
There are 28 different species of cacti in the monument, ranging from the giant saguaro to the miniature pincushion. These cacti are all highly adapted to survive in the dry and unpredictable desert. They use spines for protection and shade, thick skin, and pulp to preserve water, unique pathways of photosynthesis at night, and hidden under their skin are delicate to sturdy wooden frames holding them together.
The monument’s namesake, the organ pipe cactus can live to over 150 years in age, have up to 100 arms, reach 25 feet in height, and will only produce their first flower near the age of 35.
The organ pipe cactus bloom in May and June, opening its 3-inch white, creamy flowers at night. Flowers will close up again by mid-morning, and very rarely remain open into the afternoon. This leaves very little time for daytime pollinators to feast on the sweet flower nectar. Lesser long nosed bats do most of the night pollination, and over the centuries, have developed a unique relationship with these cactus.
The fruit of the organ pipe ripens just before the summer rains and splits open to reveal a bright red seed-studded pulp. These seeds, with the aid of nurse plants or rocks, have the potential to grow from small seedlings into hundred-armed giant.
Organ pipe cactus thrive in the Sonoran summer. High temperatures and the monsoon rains of July and August trigger the greatest cactus growth. Within the monument boundaries, an average organ pipe cactus stem grows about 2.5 inches a year.
Highway 85 cuts through the monument from north to south. From the Kris Eggle Visitor Center you can take two drives. Both are unpaved but well maintained.
Toward the east is the Ajo Mountain loop drive, the most popular scenic drive in the monument. It is a beautiful 21-mile, one-way desert tour usually passable by normal passenger cars. RVs over 24 feet are prohibited, due to the twisting and dipping nature of the road.
The loop offers amazing views of barrel, saguaro, and organ pipe cactus. And in the spring, the desert floor can be filled with such wildflowers as brittle bush, Mexican poppies, globe mellow, owl clover, and lupine. If you keep a keen eye out, you also might also see desert bighorn sheep, deer, coyotes, and javelina.
A self-guided-tour pamphlet, which can be purchased in the Kris Eggle Visitor Center for $1.00, describes 22 stops along the way and greatly enhances the experience. For example, the third stop is at a large saguaro, where visitors can learn many things about the stately cactus. Its flowers bloom in May and June, its fruit maturing a month later. Many animals dine on the fruit’s red pulp and its tiny black seeds. The Tohono O’odham people grind its seeds into a buttery substance that is considered a delicacy. Saguaros stay generous past their fruit-bearing prime: Their decaying, hole-dotted trunks provide shelter for birds, and their “skeletal ribs” once constituted building materials for American Indians.
Interpretive programs are offered January through March. Take the opportunity to spend three hours with a ranger driving on the Ajo Mountain drive. Since space on this van tour is limited to 10 per day, interested visitors should sign up early at the Kris Eggle Visitor Center.
The Puerto Blanco drive west of the visitor center provides access to the Pinkley Peak Picnic Area, Red Tanks trail head, Senita Basin, and Quitobaquito Springs. The drive offers stops along the way that provide wonderful views and information on the ecology and culture of the Sonoran Desert. The entire 37 miles of the drive was completely reopened in 2014. Be advised that many travel books and websites do not reflect this change. High clearance vehicles are recommended beyond Pinkley Peak.
Twin Peaks Campground offers 208 sites that are generally level, widely spaced, and landscaped by natural desert growth. The campsites will easily accommodate big rigs and are available on a first-come first-served basis. As well, Alamo Campground has four well-spaced, primitive spots.
Our experience in this extraordinary desert—is exotic, inviting, and utterly unforgettable.
Take your time.