The white Toyota Tacoma lurched along the dirt road, up and down hills, scraping against the sides of the truck with a high-pitched whine. Naomi Fraga, her hair in pigtails under a baseball cap, drove like a slightly more cautious Indiana Jones guided by an old map.
He stopped the vehicle in an elevated position overlooking an expanse of rocks and Joshua trees in eastern Kern County, about 170 miles northeast of Los Angeles.
“This is right where they are supposed to be,” he said.
Dr. Fraga, 43, was on a treasure hunt, but not for gold or jewelry. She was scouring the desert for delicate flowers so small they are called “belly flowers” because botanists must turn upside down to see them properly.
This winter’s relentless rain produced an abundance of blooms across California this spring, delighting residents with vibrant colors in places like the Antelope Valley California Poppy Preserve, where visitors have lined up to take selfies with the displays. . After unusually wet periods like this, species emerge that haven’t been seen in years.
For Dr. Fraga, a botanist at the nonprofit California Botanical Garden in Claremont, this spring provides an extraordinary opportunity to document the existence of rare plant species so they can be saved from the brink of extinction.
This stretch of central California, where the Sierra Nevada Mountains meet the Mojave Desert, was once part of a vast, untouched landscape. Billions of microscopic seeds lay dormant in the top layer of the earth for years, even decades, until conditions were just right for them to emerge as wildflowers.
Historically, spring has been characterized by a dazzling array of flowers across the West, each suited to its particular setting. (California, one of the most biodiverse places on the planet, is home to at least 2,400 rare plant species.)
Over time, farms, homes, and off-road vehicles have eroded patches of rare plant habitat: a hillside here, a meadow there. Climate change has changed when, where and how much it rains. Even in places where carpets of wildflowers still flourish in wet years, the crowds can jeopardize their future.
So this spring and summer, Dr. Fraga and other rare plant biologists are in an exciting race to find wildflowers before they disappear again.
The ultimate goal of botanists is to secure rare or endangered species designations for the most threatened plants. That can lay the groundwork for legally compelling land managers to make adaptations for threatened species. (For example, the Center for Biological Diversity has made protecting wildflowers a key part of its longstanding fight against the development of Tejon Ranch, where nearly 20,000 new homes have been proposed north of Los Angeles.)
To earn rare or endangered species designations, Dr. Fraga and her colleagues must first prove that the plants still exist. Dr. Fraga may be the only person equipped to do that with the plants she studies, said Katie Heineman, vice president of the Center for Plant Conservation.
“Without it, there would be no knowledge of that plant species worldwide,” he said. “It’s what drives conservation action: having fully trained people to observe these plants in the field.”
On this trip, Dr. Fraga was looking for a species known as the Kelso Creek Monkeyflower, with flowers that are half golden yellow and half deep brown.
“Each of us has our own kind of pet,” said Dr. Fraga. “I wish we could do more. We keep talking about the extinction crisis, but we only know if things are going extinct if you track them.”
Dr. Fraga sees the broad acceptance of habitat destruction in California as something of a slippery slope. Each flower represents millennia of evolution. If we accept the extinction of a dark monkey flower, he worries, where might it end up? And what consequences could the alteration of complex ecosystems have?
Every spring, Dr. Fraga and her fellow conservationists, including amateur botany enthusiasts who use apps like iNaturalist, try to document as many rare plant populations as they can.
Scientists must plan meticulously to find targets in full bloom. If they arrive at a location hours in advance, the flowers may still be hidden in their buds, making them difficult to study. If they arrive too late, the flowers may have already wilted from the heat.
Dr. Fraga focused on monkey flowers after stumbling into a scientific career she never thought she would have.
Her father, a Mexican immigrant who worked as a trucker, thought she should become a kindergarten teacher after being the first in her family to attend college. But at age 20, a mentor of hers, also a Mexican-American woman, took her on her first hike, looking for a rare herb. Her feet ached from ill-fitting boots, but she was hooked. Dr. Fraga later felt the excitement of the discovery; she has found five new species of monkeyflower.
As a Latina, Dr. Fraga is a pioneer in a field long dominated by white males, dating back to the 18th century when European settlers traveled the world and built collections of exotic plant specimens, many of which are used by scientists today. (The oldest specimen in the California Botanical Garden’s collection dates from 1750.)
“It’s a complicated legacy,” he said, stopping near a purple owl clover, a native wildflower.
Further down the road, Dr. Fraga examined clumps of desert dandelions and butter-colored scale buds, hurried past rows of pale cream tops. Insects buzzed and lizards crossed his path.
It stopped suddenly. “Oh my god! A hybrid!” she cried.
A Kelso Creek Monkeyflower had somehow crossed with a Rock Jasmine Monkeyflower, another close species. She had never seen one in person before. He stopped to photograph the plant and take detailed notes on its characteristics.
“Actually, you’re coming with me,” he said, after looking at another. He carried the plant back to the truck, where he pressed it between the pages of the Claremont Courier.
But the Kelso Creek Monkey Flower, his target for the day, continued to prove elusive. She frowned, puzzled. “This is a good habitat,” she said.
He met closely with three of his students and the group consolidated into two trucks. They splashed through the persimmon-tinged Kelso Creek, for which the flowers are named, to check out one more spot where Dr. Fraga had seen a small bloom of a few hundred plants the year before.
On the other side of the stream, they saw a field that, from afar, looked like green bushes and cacti. But as they got closer, the botanists looked on in amazement: a sea of tiny plants with yellow and maroon flowers rolled past. There were millions, the group later estimated.
“It’s a micro-super flower!” gasped Courtney Matzke, 35, one of the students.
They had finally found their flowers. The afternoon sun was beating down.
It was time for Dr. Fraga and her students to get down to work.