Although the very mention of Arizona may cause some people to turn the air-conditioning on full blast, this state is much more than a searing landscape of cacti and mesquite trees. From the baking shores of the lower Colorado River to the snowcapped heights of the San Francisco Peaks, Arizona encompasses virtually every North American climatic zone. Cactus flowers bloom in spring, and mountain wildflowers have their turn in summer. In autumn, the aspens color the White Mountains golden, and in winter, snows blanket the higher elevations from the Grand Canyon's North Rim to the Mexican border.

But it's the Sonoran Desert, with its massive saguaro cacti, that most people associate with Arizona, and it is here in the desert that the state's two largest cities -- Phoenix and Tucson -- are found. Due in large part to the relatively plentiful rains in the region, the Sonoran Desert is one of the world's greenest and most biologically diverse deserts. In Arizona, rain falls during both the winter and the late summer. This latter rainy season, when clamorous thunderstorms send flash floods surging down arroyos, is known as the monsoon season and is the most dramatic time of year in the desert. The sunsets are unforgettable, but so, too, are the heat and humidity.

Before the introduction of dams and deep wells, many Arizona rivers and streams flowed year-round and nurtured a surprising variety of plants and animals. Today, however, only a few rivers and creeks still flow unaltered through the desert. They include Sonoita and Aravaipa creeks and the San Pedro, Verde, and Hassayampa rivers. The green riparian areas along these watercourses are characterized by rare cottonwood-willow forests and serve as magnets for wildlife, harboring rare birds as well as fish species unique to Arizona. Preserves near Prescott, Patagonia, and Sierra Vista protect the last few riparian forests.

Outside the desert regions, there is great diversity as well. In the southern part of the state, small mountain ranges rise abruptly from the desert floor, creating refuges for plants and animals that require cooler climates. It is these so-called sky islands that harbor the greatest varieties of bird species in the continental United States. Birds from both warm and cold climates find homes in such oases as Ramsey, Madera, and Cave Creek canyons.

Although rugged mountain ranges crisscross the state, only a few rise to such heights that they support actual forests. Among these are the Santa Catalinas outside Tucson, the White Mountains along the state's eastern border, and the San Francisco Peaks north of Flagstaff. However, it's atop the Mogollon Rim and the Kaibab Plateau that the ponderosa pine forests cover the greatest areas. The Mogollon Rim is a 2,000-foot-high escarpment that stretches from central Arizona all the way into New Mexico. The ponderosa pine forest here is the largest in the world and is dotted with lakes well known for their fishing. The Mogollon Rim area is also home to large herds of elk. At more than 8,000 feet in elevation, the Kaibab Plateau is even higher than the Mogollon Rim, yet it is through the Kaibab Plateau that the Grand Canyon cuts its mighty chasm.

Arizona Flora & Fauna

Saguaros & Their Spiny Friends

From the diminutive hedgehog to the stately saguaro, the cacti of the Sonoran Desert display a fascinating variety of shapes and sizes. While your first thought is usually to give them a wide berth, Arizona's cacti are worth a closer inspection, especially in the spring, when their large, waxy flowers paint the desert with splashes of color. May is probably the best all-around month for seeing cactus flowers, but you can see them in April and June as well.

The best natural areas to see cacti (it's okay to say cactuses, too) are Saguaro National Park (outside Tucson), Organ Pipe Cactus National Monument (100 miles west of Tucson), Sabino Canyon Recreation Area (in Tucson), Picacho Peak State Park (near Casa Grande), and South Mountain Park (in Phoenix). To learn more about cacti, visit the Desert Botanical Garden in Phoenix, Boyce Thompson Southwestern Arboretum in Superior, or Tucson's Arizona-Sonora Desert Museum.

Saguaro Cactus -- The saguaro (pronounced sa-hwah-ro) is the largest cactus of Arizona's Sonoran Desert and grows nowhere else on earth. (Saguaro throughout the state are protected by law.) Reaching heights of as much as 50 feet, saguaros are the redwoods of the desert, and often grow in dense stands that resemble forests. Saguaros are a slow-growing cactus; a 6-inch-tall cactus might be 10 years old, and it can take 75 years for a saguaro to sprout its first branch. The oldest-known saguaros are around 200 years old, and some have more than 40 arms.

To support their great size in such an arid environment, saguaros have a highly efficient root system that can be as large as 100 feet in diameter. These roots soak up water quickly and store it in the spongy interior of the cactus. After a rainstorm, a mature saguaro can weigh as much as 7 tons and survive for up to 2 years without another drop of water. Supporting this great mass is an internal framework of sturdy ribs, while the exterior of the cactus is pleated so that it can expand and contract as it takes up and loses water.

Each spring, waxy white flowers sprout from the tips of saguaro arms. These flowers are pollinated by white-winged doves and lesser long-nosed bats that come from hundreds of miles away in Mexico just for saguaro flowering season. Other animals that rely on saguaros include Gila woodpeckers and elf owls that nest in holes in saguaro trunks.

The Tohono O'odham people, natives of the Sonoran Desert, have long relied on saguaro cactus fruit as an important food source, even making a traditional ceremonial wine from the red, seedy pulp. So important has the saguaro harvest been in the past that the Tohono O'odham consider the saguaro harvest the start of the new year.

Organ Pipe Cactus -- This close relative of the saguaro takes its name from its many trunks, which give it the appearance of an old pipe organ. The organ pipe cactus is even more frost-sensitive than the saguaro and lives only in an area 100 miles west of Tucson on both sides of the Mexican border. This population of stately cacti has been preserved in Organ Pipe Cactus National Monument.

Barrel Cactus -- When mature, these cacti look much as their name implies and can be confused with young saguaros. However, the barrel cactus can be distinguished by its fishhook-shaped spines, which are usually yellow or red. This is the cactus that for years has been touted as a source of life-giving water to anyone lost in the desert. The liquid in this cactus's spongy interior is actually quite bitter and foul-tasting. However, the same spongy pulp, when cooked in sugar water, becomes very tasty.

Cholla Cactus -- The cholla (pronounced choi-yah) is the most dreaded of all the Arizona cacti. Its spines are long, plentiful, sharp, and brittle. To brush up against a cholla is to experience certain pain. Here in Arizona, there are several species of cholla, most of which resemble small trees. They go by such graphic names as jumping cholla, which is said to throw pieces of its spiny branches at unwary passersby; teddy bear cholla, which is so covered with spines that it looks fuzzy; and chain fruit cholla, on which fruit hang in fragile, spiny chains. The chollas are favored nesting spots of cactus wrens and doves. Give chollas a wide berth.

Prickly Pear Cactus -- This is one of the largest and most widespread families of cacti and can be found throughout the United States, not just in the desert. They are also among the most commercially important cacti. The flat stems or pads (known as nopales in Spanish) of one species are used in Mexican cooking and can be found both fresh and canned in markets in Arizona. The fruit of the prickly pear is also edible and is relished by both humans and animals. Here in Arizona, it's possible to find prickly-pear jams and jellies, as well as prickly-pear ice cream and margaritas.

Roadrunner, Coyote & Other Desert Denizens

Just as cacti have adapted to the desert, so too, have the animals that live here. Many desert animals spend the sweltering daytime in burrows and venture out only in the cool of the night. Under cover of darkness, coyotes howl, rattlesnakes and great horned owls hunt kangaroo rats, and javelinas root about for anything edible. Gila monsters drag their ungainly bodies through the dust, while tarantulas tiptoe silently in search of unwary insects.

Greater Roadrunner -- "Roadrunner, if he catches you, you're through." Now, I know that the words from the cartoon theme song were meant as a warning to the roadrunner that the wily coyote was after him, but, if you happen to be a snake or a lizard and a roadrunner catches you, you are definitely through. Real roadrunners, which prey on snakes and lizards, are the largest North American member of the cuckoo family and can run 15 mph. Although they are able to fly, they rarely do. Roadrunners are curious creatures; I once saw one running around in a Tucson brewpub parking lot checking out new customers as they got out of their cars.

Coyote -- No other creature better symbolizes the desert Southwest than the coyote. Celebrated as the Trickster in Native American stories, coyotes are curious animals that have adapted well to life amid the ever-expanding cities and towns of Arizona. They are often seen boldly strolling across not just remote stretches of highway, but suburban streets as well. I once watched a coyote curiously following a foursome on a golf course in Scottsdale. Nothing captures the essence of the desert quite like the crazy cackling of coyotes at sunset.

Gila Monster -- Despite the fearful name, this is actually just a lizard, albeit a large, ugly, and poisonous lizard. In fact, Gila monsters are one of only two poisonous lizards in the world. With their mottled black-and-pink coloring, their warty-looking scales, and their fat, stubby tails, these slow-moving lizards are indeed a monstrous sight. However, because they are relatively uncommon, your chances of encountering one in the wild are slight. By the way, the Gila monster's warty appearance is caused by osteoderms, bony plates that were common among dinosaurs but are rare in modern reptiles.

California Condor -- Although they are certainly ugly, California condors can have a wingspan of 9 feet, which gives them the largest wingspan of any North American bird. In 1987, there were only 22 California condors left on earth. At that point, all of them were captured so that they could be bred in captivity. Today, there are nearly 300 of the huge birds, and many of them live in Grand Canyon National Park and Vermilion Cliffs National Monument, where a release site is located. Condors are also often seen in the vicinity of Grand Canyon Village on the South Rim of the Grand Canyon.

Collared Peccary -- Known in Arizona as javelinas (pronounced hav-uh-lee-nuhs), these strange-looking creatures look a bit like long-haired, neckless pigs. Javelinas are very well adapted to life in the desert; they can even eat prickly pear cactus -- spines and all. While not normally aggressive, they are so nearsighted that in their hurry to get away from you, they might run straight at you, not realizing where you're standing. Several times over the years I have spooked javelinas on trails in the Tucson area. I've always been just as startled by them as they have been by me.

Tarantula -- Okay, I know these giant arachnids are about as creepy as a crawly thing can be, but actually they're neither aggressive nor particularly poisonous. However, with their 2-inch bodies, 4-inch legs, and Hollywood horror-movie reputation, they often inspire terror in Arizona visitors. After late-summer rainstorms, male tarantulas can often be seen wandering across roads. They're wandering in search of a mate, and after mating, the male usually dies within a few months. Female tarantulas, however, can live for 25 years or more.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.