When the desert blooms in spring, as it has done in recent weeks, it is an eye-popping spectacle.
There are the vivid yellow blooms of blue palo verde (PAH-lo VAIR-day) and sweet acacia (uh-KAY-shuh) trees, the blazing red tips of a spiny plant known as an ocotillo (oh-coh-TEE-yo), and the vibrant purple and orange of desert wildflowers.
The desert, though, is not where most people expect to see such a dazzling display of color.
After all, imagine living in a place where the sun shines brightly an average of 320 days out of 365. Here, rainfall averages about seven inches a year, and the temperature in summer can reach 120 degrees F. In winter, temperatures dip below freezing.
You'd think that such a climate would be too extreme for plants and animals to live in - let alone humans.
But here in the Sonoran Desert, which stretches from Arizona to California and all the way down both sides of the Gulf of California in Mexico, plants, animals, and humans thrive - especially in springtime.
How? Survival in the desert is a remarkable story of adaptation, says Mark Dimmitt of the Arizona-Sonora Desert Museum in Tucson, Ariz. For every living thing, water is essential to survive.
More than half of the desert's 2,000 kinds of plant life are annuals. That means they complete a life cycle - growing from seed, blooming, setting seeds, and dying - in one growing season. That means the plants are underground, invisible to humans, most of the year.
How much water they get isn't as important as when they get it, Dimmitt says. Spring flowers in the desert come up in large numbers only when there's been a soaking rain the previous fall, according to Dimmitt. He is the museum's associate director of science.
Other annuals, such as Arizona poppies and devil's claws, sprout within days after a summer desert downpour. They grow rapidly in the hot weather, and complete a life cycle in just a few short weeks, Dimmitt says.
Other plants adapt to the dry desert in unique ways.
Cactus and agave (uh-GAV-ay) store water within themselves to survive from one rain to the next. They collect the water using a huge, shallow root system that fans out just below the surface to absorb the rainfall.
Animals, too, must adapt to the desert to survive. Lizards, snakes, and tortoises have scaly skins or hard shells to keep moisture inside.
Many desert animals avoid the heat of the day by resting in the shade. Others burrow underground. The temperature just a few inches below the surface is 12 to 15 degrees cooler.
Snakes and lizards may be cooler in their underground lairs, but they face another problem: How do they keep from breathing in sand? Some have valves on their nostrils that can take in air without sucking in sand. A fringe toad lizard even has something like a sink trap that catches the sand. Then the lizard coughs it out.
ON a recent warm spring day in Phoenix, as the temperature approached 100 degrees, some area schoolchildren got to see desert plant and animal life firsthand during a walking tour of the Desert Botanical Garden.
Second-graders Christopher Baltierrez and Hiedra Martinez were delighted to see flowering cactuses. They also saw scorpions, lizards, frogs, and turtles coming out of their winter burrows to warm themselves in the spring sun.
"It was fun," the youngsters agreed, taking a break at the end of their walk and resting beneath the shade of lacy palo verde and mesquite (mess-KEET) trees before boarding a school bus to go back to their classroom.
Christopher and Hiedra's field trip was the highlight of weeks of study in which the students learned about the desert through classroom reading, language, science, and math instruction.
ONCE they go back to the class, teacher Eugenia Wach says, they will write in their journals and describe what they have studied and seen.
"The desert is not something dead," Ms. Wach said. "It is active and something that they can maintain."
Many people think of the desert as an unfriendly place. It's a place to be gotten through as quickly as possible, they think. But this view is changing.
People who drive through it often see the least-interesting parts of the desert - the flat valleys. That's where the engineers put the roads because that's the quickest way through.
The desert's diversity lies off the beaten path, Dimmitt says. And slowly, the beauty of the desert is being recognized.
"To the people who come here, the desert is a powerful environment," he says. "You form an opinion about it early: Either you love it or hate it. If you look deeper, it's not the barren wasteland that you might think at first."