Ajo Mountain Drive Guide

Desert Adaptations

National Park Service

U.S. Department of the Interior

Organ Pipe Cactus National Monument

National Park Service 

1

How to Use This Guide

This guide is intended to help you enjoy Organ Pipe Cactus National Monument by better 

understanding the Sonoran Desert. Keep notes on any questions that come to mind and 

when you return to the Kris Eggle Visitor Center, ask a ranger.

The Ajo Mountain Drive is a 21-mile (34 km) graded, one-way dirt road. It winds and dips 

over a route that blends with the primitive nature of the landscape. The drive will take 

approximately 2 hours.

Driving slowly and taking advantage of the stops will provide the best opportunities to 

enjoy the desert. The road has been designed so that a passenger car, driven with caution, 

may be taken over it safely. This route provides access to some of the finest scenery in the 

monument.

Each numbered stake beside the road corresponds to the numbered paragraph in the 

guide. Each stop in the guide indicates the distance from the fee station at stop #1.

There are four picnic sites provided along the drive. Stops #6 has a ramada to provide a 

shaded picnic site and Estes Canyon after stop #11 has a ramada and restrooms.

Some Reminders

• Trailers, buses and RVs over 25 ft (8 m) 

are prohibited on Ajo Mountain Drive

• Fires are not permitted.

• Water is not available anywhere along the 

drive so carry plenty with you.

• Camping is not allowed on the drive.

• Pets are not allowed on trails or in the 

backcountry. They must be leashed 

at all times. Please do not leave pets 

unattended.

• Do not cross washes when flooded.

• Do not pick up hitchhikers.

• Report any suspicious activity to park 

staff immediately. Do not contact any 

suspicious persons. If you see them in 

distress, contact a ranger for help.

Leave No Trace

• Be considerate of other visitors

• Respect wildlife

• Travel on trails or durable surfaces

• Leave what you find

• Dispose of waste and trash properly

• Plan ahead and prepare

Copyright: Leave No Trace Center for Outdoor Ethics: www.LNT.org
Ajo Mountain Drive Guide 2

Sonoran Lingo - Speak Like a Local

Saguaro – sa-WAH-row 

Creosote – CREE-oh-sote 

Cholla – CHOY-yah 

Ajo – AH-hoe

Palo verde – PA-loh VAIR-deh 

Bajada – bah-HAH-da 

Estes – ESS-tees 

Jojoba – hoe-HOE-bah 

Mesquite – mess-KEET 

Pinacate – PEE-nah-CAH-teh

Ocotillo – Oh-koh-TEE-yo 

Diaz – DEE-ahz 

Tohono – Tow-HOE-no

O’Odham – Oh-oh-thaam 

Gila – HEE-lah 

Mojave – Moe-HAH-vee 

Chihuahua – Chee-WAH-wah 

Tinaja – tee-NA-hah 

Cubabi – cu-BAH-bee 
National Park Service 

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Stop 1

Mile 0 [km 0]

The Sonoran Desert

 Welcome to Organ Pipe Cactus 

e 

 Based on plant evidence, scientists grow after sufficient rainfall in winter or 

summer. Most animals that live here are 

either nocturnal or crepuscular (dusk- or 

dawn-active) to thwart the high daytime 

temperatures. These adaptations, along 

with many more, allow the Sonoran Desert 

life to thrive.

 Welcome to the Green Desert! As 

you travel down this road, we encourage 

you to travel slowly, pay attention to 

details, and discover some of these unique 

relationships for yourself.
Ajo Mountain Drive Guide 4

Stop 2

Mile 1.4 [km 2.3]

The Desert Smells Like 

Rain 

 Decorating the landscape of the 

Sonoran Desert is the creosote bush. This 

olive green shrub you see all around you is 

one of the most drought-tolerant plants in 

North America. Long after the soil is too 

dry for most species, creosote still manages 

to absorb water. Its adaptations allow it to 

survive without water for two years before 

completely dying.

 This supple plant sports small yellow 

blossoms in the spring and summer. It may 

occasionally bloom during other times of 

the year if rainfall is sufficient. The seeds 

are gray fuzzy balls that resemble droplets 

of water hanging from the branches. The 

waxy coating on creosote’s leaves protects 

the plant from excessive water loss. Locals 

often say that the Sonoran Desert “smells 

like rain” because of the intoxicating 

aroma the leaves give off during a rain 

storm or on a foggy winter morning.

 Creosote is found abundantly, all 

over the southwest, in three deserts – the 

Chihuahuan, Mojave and Sonoran. It also 

is very long-lived, creating clonal colonies; 

one found in California is believed to be 

over 10,000 years old and is considered one 

of the oldest single living organisms on the 

planet.

 Creosote is useful to many desert 

species. The kangaroo rat likes to build 

its nest within the roots of the creosote 

bush. The seeds are a life source to many 

jackrabbits. The desert kit fox prefers 

to make its den within the roots of the 

creosote. Many cactus species use the 

creosote for shelter when the cactus 

is young and establishing its own root 

system.

 This unassuming shrub originated in 

South America but it is clearly one of the 

most well-adapted plants found in the 

monument. The creosote has not only 

made its home in the heart of the Sonoran 

Desert but in the hearts of many desert 

natives as well.
National Park Service 

Stop 3

Mile 1.9 [km 3.1]

A Sonoran Desert Icon

 You would think that the saguaro crowns of the cacti.

 The timing of the fruit ripening is 

impressive. Flowers appear in May and 

June when the desert is at its hottest and 

driest. The nectar is the only moisture in 

town, attracting important pollinators like 

birds and bats. The fruits ripen in July, in 

time for many animals to eat the delicious 

red fruits and transport thousands of seeds 

to new homes. Once the seeds are spread 

and the monsoon rains start, those seeds 

have the chance to grow into new giant 

saguaro.

 Even with all of the saguaro’s 

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Ajo Mountain Drive Guide

Stop 4

Mile 3.9 [km 6.3]

Our Namesake Cactus

 Organ Pipe Cactus National 

 In June and July, flowers and fruits 

Stop 5

Mile 4.7 [km 7.6]

At Home in the Desert

 The sounds of thunder and drumming 

...established by President Roosevelt 

and protects the only natural 

habitat within the United States for 

the organ pipe cactus.

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National Park Service 

 Have you ever walked across a sandy 

The summer monsoons offer a welcome 

respite from the dry landscape and 

tortoises take advantage of these rains, 

increasing their outside activity.

Stop 6

Mile 5.5 [km 8.9]

Picnic Area with ramada

Farming a Dry Land

 To your left is Diablo Wash, one Dams were built in strategic places to divert 

the floodwaters into irrigation ditches 

where the water would be most useful. In a 

months time, and with less than four inches 

of rain, crops would mature and produce a 

staple food source, without which humans 

could not have survived this environment.

 The Tohono O’odham continued these 

dry-land farming practices learned from 

their Hohokam ancestors. They built shade 

structures called ramadas, similar to those 

in our picnic areas, to shelter them from the 

harsh summer sun as they lived alongside 

the wash. They spent months planting 

crops and harvesting saguaro and organ 

pipe fruits, all the while praying and waiting 

for the life-sustaining rains to come.

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Ajo Mountain Drive Guide 8

Stop 7

Mile 6.0 [km 9.7]

Picnic Area

Hermana Means Sister

 Scenic views are spectacular from the for hummingbirds, coyotes and javelina. 

Humans have traditionally used these 

pathways as well. Other species, like the 

endangered Sonoran Pronghorn, prefer 

the open creosote flats. Biologists from 

both Organ Pipe and El Pinacate are 

studying wildlife migration, determining 

human impacts on wildlife and how the 

two park sites can better manage wildlife 

populations. State, federal and Mexican 

biologists have created the Sonoran 

Pronghorn Recovery Team, which conducts 

aerial surveys of pronghorn, provides 

support to local parklands and operates a 

captive breeding program.

 This relationship with our sister park 

allows us to share information across a 

political boundary, collaborate efforts to 

protect animals like the pronghorn and to 

cooperate with each other in preserving 

and conserving two vividly different wild 

lands.

Cubabi Mountains

Sonoyta, Mexico Campground
National Park Service 

Stop 8

Mile 7.1 [km 11.4]

The Prickly Pear

 Many species of prickly pear cacti are 

 These cacti are very important to 

Stop 9

Mile 8.4 [km 13.5]

Take a Closer Look

 Another cactus that is human-friendly 

is the organ pipe cactus. The fruit is made 

into sweet jams. As you look to the right 

you will see a phenomenon that does not 

disturb the fruit cycle. This organ pipe has 

an abnormal growth on an arm growing out 

of the center of the cactus. This growth is 

called a “crest” and can occur in almost all 

plant species.

 A typical organ pipe cactus has 

 Keep on the lookout for more crested 

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Ajo Mountain Drive Guide

Stop 10

Mile 8.7 [km 14]

The Cooler Climate of 

Canyon Country

 The Ajo Mountains receive more rain cling to rocky slopes and steep ravines. 

The mountain environment is especially 

attractive to turkey vultures, eagles and 

ravens that nest in the canyons and ride the 

air currents that canyons provide. Caves 

and rock shelters within the canyon walls 

are also great roosting places for bats. The 

lesser long-nosed bats, which have already 

been mentioned, especially like to roost in 

the cool shaded canyons during the heat of 

a summer day.

 Just up the road is the Arch Canyon trailhead 

Stop 11

Mile 10.4 [km 16.7]

Wintering in the High 

Country 

 Another higher elevation plant country of Organ Pipe Cactus National 

Monument. These pits are associated 

with the Hohokam who cultivated agave 

for ceremonial purposes. Why were the 

Hohokam at the top of the Ajo Range?

 Archeologists believe that the 

Hohokam tradition was to move to the 

high country canyons after fall harvest in 

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National Park Service 

the valleys. Canyons, like Estes Canyon 

below and to your left, served as winter 

homes and watchmen were located at the 

tops of mountains to guard the community 

against raiders. The Tohono O’odham 

also used these canyons as winter homes. 

They were likely hunting mammals. These 

higher elevations also afforded a chance 

to catch more water. Snow and rain were 

more likely in the mountains. It is easy to 

imagine the people of the past making their 

way on foot up that steep rugged hill. The 

promise of water in dependable tinajas, 

natural catchments in the rock that hold 

rain water, were their only source of water 

for miles. The Hohokam and the Tohono 

O’odham adapted to the desert by moving 

biannually to find food and water. Their 

migratory routes were always associated 

with tinajas, springs or other water sources 

and are still visible in the monument today. 

 Ahead is Estes Canyon, the midpoint of the Ajo Mountain 

Stop 12

Mile 11.3 [km 18.2]

The Essential Jojoba

 the extreme desert heat by keeping their 

leaf edges facing the harsh midday sun, 

thus reducing evaporation of precious 

water from broad, flat leaf surfaces.

 The foliage provides year-round 

browse for animals like bighorn sheep and 

whitetail deer. The nuts are consumed by 

many animals, including squirrels, rabbits, 

birds, as well as humans. During times of 

hunger native people would eat the fat-rich 

seeds to suppress their appetites until food 

was again available.

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Ajo Mountain Drive Guide

Stop 13

Mile 12.3 [km 19.8]

The Trees of Life

 The mesquite tree has long inhabited 

the land you see before you. The fruit is 

high in carbohydrates and attracts many 

different herbivores. The mesquite adapted 

seed dispersal so that when seedpods 

were eaten in great quantities, they were 

dispersed across the land. Rabbits, 

packrats, javelina and coyote all depend 

on the seasonal seedpods for food. These 

animals, and others, help to scatter the 

mesquite seeds across the desert.

 In the 1500s, missionaries introduced 

the cow, which allowed for even greater 

seed dispersal. Cattle no longer range 

in the monument but the abundance of 

mesquite serves as a reminder of their 

presence. 

 Often called the “Tree of Life”, many 

desert-dwellers owe their survival to the 

mesquite tree. The seeds were, and still are, 

ground into flour used for breads. These 

seeds have more protein than soybeans and 

were a major food source for the Tohono 

O’odham. 

 Another tree that sustains life in the 

desert is the palo verde. With its green 

trunk and branches, the palo verde has a 

very clever way of conserving moisture. By 

not having leaves during the hot season, 

it can photosynthesize and respire (that is 

to create energy and breathe) through its 

trunk, thus conserving water.

 The palo verde can also serve as a 

nurse tree. Saguaro seeds need shelter 

from a nurse plant such as a creosote or 

palo verde tree. These plants protect the 

young cactus from sunburn, torrential 

floods and the occasional winter frosts. 

Nurse trees such as the palo verde, 

mesquite and ironwood even fertilize the 

young cacti as the trees fix nitrogen from 

the air into the soil for themselves. The 

young cactus is “nursed” as it grows up 

tall and strong, spreading its shallow root 

system out to collect rain as it falls. This 

is not good news for the nurse plant. As 

the cactus roots spread only 3-4 inches 

below the surface of the soil, what started 

as a shelter becomes a battlefield for water. 

The saguaro proves victorious. Many 

of the monument’s larger saguaros are 

surrounded by remains of their dead nurse 

trees.

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National Park Service 

Stop 14

Mile 12.7 [km 20.4]

Traveling in the 

Footsteps of History

 In the 1680s, Father Eusebio Francisco region. Bull Pasture gets its name from the 

monuments’ ranching era; Twin Peaks is 

named for its double-peaked appearance; 

Pinkley Peak commemorates Frank Pinkley, 

Superintendent of Southwestern National 

Monuments 1923 – 1940. Behind each 

name is a story.

 The Diaz Mountains are named 

for Captain Melchior Diaz, leader of 

a 15 member group in the Coronado 

expedition 1539-1542. In January 1541, when 

the expedition was close to here, Diaz 

suffered a freak accident and was mortally 

wounded. Diaz’s men had no choice but to 

abandon any further explorations. During 

his fourteen months and over 3500 miles of 

reconnaissance on behalf of the Coronado 

expedition, Melchior Diaz left a valuable 

legacy. The information he gathered on the 

native peoples he encountered offers the 

modern reader a glimpse into a way of life 

prior to European contact.

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Ajo Mountain Drive Guide

Stop 15

Mile 13.1 [km 21.1]

Waiting For Rain

 pollinate the plant and are vital to the 

ocotillo’s survival. The nectar found within 

each tubular flower is a vital energy source, 

crucial to the hummingbird’s survival 

during its long and arduous migration. 

This mutually beneficial relationship is 

another example of adaptation to the 

desert environment.

 These plants are not only beautiful but 

useful as well. Ocotillos are resilient and 

have been used for roofs and living fences 

by the Tohono O’odham and other people 

in the area. When the branches are cut 

and planted in the ground, they often root, 

surviving to bloom again during the rainy 

seasons, creating a beautiful and useful 

fence or a lovely home. 

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National Park Service 

Stop 16

Mile 15.1 [km 24.3]

A Forest of Spines

 

hook into the coat or flesh of the passer-by 

and the cholla joint is transported to a new 

location. If the conditions are favorable 

where it falls, the cholla joint might grow 

into a new plant. This cactus is sometimes 

referred to as a “jumping cholla” as the 

cholla joints seem to jump off the plant and 

attack unsuspecting passers-by. Reality is 

they don’t jump; they are just very efficient 

at picking up a ride. As you can imagine, 

picking up these hitchhikers is painful. 

Adapt your habits to the desert by using 

caution and carrying tweezers to remove 

any cholla joints when you are out walking.

 You may be surprised to learn that 

some birds will take up residence in these 

cacti; the spines prove some defense against 

desert predators. As you continue, look for 

cactus wren nests; they resemble footballshaped clumps of weeds with a side hole 

big enough for the birds to go in and out.

Stop 17

Mile 16.9 [km 27.2]

Teddy Bear Pass

 Do not be deceived by the cuddly 

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Ajo Mountain Drive Guide

Stop 18

Mile 17.3 [km 27.8]

What Does the Future Hold?

 

 We hope you enjoyed your time on “It is not necessary to change. 

Survival is not mandatory.”

Dr. W. Edwards Deming

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National Park Service 

Some Titles to Consider:

About Organ Pipe Cactus National Monument:

Trails Illustrated Topographic Map of Organ Pipe Cactus National Monument

Checklists of Native Species

Where Edges Meet

Natural History:

The Desert Smells Like Rain

A Natural History of the Sonoran Desert

Dry Borders

Parks After Dark

Cultural History:

Fragile Patterns

Food Plants of the Sonoran Desert