Kerry Knudsen's higher calling keeps him low to the ground.
He bellies up to crumbling boulders and roots among the decay of fallen trees, just to get nose-close to something on the order of mold or slime.
"Beautiful," Knudsen said.
The object of his affection: lichens. The former construction worker is a self-taught lichenologist, a specialty that makes him one of the world's rarest and least-heralded breeds of botanist, amateur or otherwise.
Knudsen's fixation is a complex, little-understood union of a fungus and an alga or bacterium, symbiotically sharing the same body. His devotion to the peculiar organisms is revealing much about the environmental health of Southern California and many regions like it.
So far, the news isn't good.
"People should be worried," said Knudsen, 53, as he climbed a steep, sandstone-ribbed trail in the Santa Monica Mountains, huffing and puffing in search of lichens hardy enough to survive near the city. "People breathe the air down there."
Most lichens are tiny and grow in patches on rock and concrete, bark and dirt, but only where the air is clean.
And though they carpet the earth in climes as harsh as the Arctic, lichens have virtually vanished from the flatlands in the Los Angeles region, and appear to be succumbing on the surrounding slopes -- largely because of smog.
"There definitely were lichens all over this area," Knudsen said, pausing on a dusty ridge, a sea breeze at his back. "They're gone now."
In their time of distress, these ancient building blocks of nature -- lichens play a role in everything from soil creation to bird nesting -- have few modern-day defenders, the folks who consider them canaries in the mine of urban air quality.
Two lichens (pronounced LIKE-ens) rate a place on the federal list of endangered species, but scientists say hundreds more might be imperiled. Left unprotected are the colorful, pencil-point blooms, along with the jumbo varieties of lichens that hang in ribbons from backcountry oaks.
Hikers can easily mistake smaller, centuries-old lichens for blotches of moss. Even conservationists overlook them.
"Have we studied them? No," said Rorie Skei, a deputy director of the Santa Monica Mountains Conservancy.
From coast to coast, all that lichens have in their corner is the handful of crusaders such as Knudsen, a husky man who wears his hair long and wild, a holdover from his counterculture youth.
His lack of formal training has not denied him the standing of a government-recognized expert, which is further confirmation of lichens' orphan status. The name itself is a slight; "lichen" derives from the Greek for "wart."
"They're not economically important," said Andrew Sanders, curator of the herbarium at UC Riverside, where Knudsen is assembling a lichen collection. "They're not crops, they're not weeds.... People kind of ignore them."
So do the check writers for research grants, Sanders added.
"Scientists go where the money is, and there's no money in lichens," Sanders said. "We're still finding species. We're still in the frontier. It's like 150 years ago for other species."
That's why Knudsen, someone willing to toil in the field for free, is prized by degree-holding lichenologists. He already has discovered several species, and hopes to compile a flora -- a descriptive guide -- of the Southern California lichens spared by tailpipes and smokestacks.
"He's at a very high professional level, doing high-caliber work," Sanders said.
Knudsen lives with his wife and their two daughters in Wildomar, located in the foothills of southwest Riverside County. He limped away from his construction career 10 years ago because of a blood-clot disorder that afflicts his legs. The boredom of early retirement, and a hobbyist's fascination with botany, led him to lichens.
"Wildomar's a lichen hot spot," he said. "One day, I walked out into my backyard and said to myself, 'There's either going to be moss or lichens here, and the first one I find I'm going to study.' I found lichens."
He told that story as he scoured the canyons of the San Jacinto Mountains, hunting for lichens 6,000 feet above the Coachella Valley. Joining him was Cecilia Reed, a National Forest Service resource specialist who is Knudsen's pupil when it comes to lichens.
"I never really got into them until I started hanging out with Kerry," Reed said, as she drove a Ford Explorer along an unpaved road, bouncing over tooth-loosening ruts.
"The Letharia we're going to see up here is about the biggest I've ever seen," Knudsen said, referring to one of the roughly 300 species of lichen thought to reside in the San Jacintos. "Letharia wouldn't do well in downtown L.A."
But there would be no Letharia sightings this afternoon. The road had become impassable, buried under a wheel-spinning blanket of spring snow.
Undeterred, Knudsen eased out of the Explorer. He set about inspecting the cedars and cabin-sized boulders that lined the road, leaning in as if to embrace them. A magnifying lens dangled from a cord around his neck, like a crude jeweler's loupe.
He bent over a knobby length of deadwood, using the lens to inspect a gray smear on the bark. The smear, it developed, was a living thing.
"This is Hypogymnia," he announced. "Looks dead, but it's alive."
Reed shook her head in amazement.
Knudsen walked up the road with a stone-in-the-shoe gait that betrayed his weakened legs. He slipped into his habit of dispensing lichen trivia:
Lichens help break down rocks into soil. Insects and caribou eat them, and the Japanese consume a group of species labeled "rock tripe." Then again, one lichen is so toxic that it has been used as a wolf poison.
Knudsen noted that much remains unknown about lichens, including the particulars of their strange marriage of fungi and algae.
The fungus depends on the alga for nutrients produced through photosynthesis, while the alga relies on the fungus for shelter and moisture. Precisely how they find and use each other is a mystery.
Lens at the ready, Knudsen stopped to examine a pale green marking in the cleft of a boulder. Another lichen, with a structure as intricate and delicate as a snowflake's.
"Xanthoparmelia," Knudsen said. "It's at least 50 years old."
There were more treasures along the road, starting with a rust-tinted Acarospora fuscata. "Typical of the lichens that were pushed down here in the ice age," Knudsen said.
A dull-silver Aspicilia. "We call them the carp. They're all over the place."
Except, that is, where the peaks give way to office towers and the chaparral has been bulldozed for subdivisions.
Thomas Nash, an Arizona State University lichenologist, believes that half of the native lichen species have disappeared from the Los Angeles Basin. Smog controls have returned lichens to some cities in modest numbers, but Nash doesn't expect a resurgence in L.A. The air is still too sullied.
"Lichens are dying off," Nash said. "People should be concerned about their own morbidity."
Irwin Brodo, a lichenologist in Ottawa, Canada, sought to stoke that concern by publishing a 795-page book on lichens in 2001. It was coauthored by two amateurs, Sylvia and Stephen Sharnoff.
"Lichens of North America" has sold about 10,500 copies, a robust total for a $70 volume, although hardly enough to fetch movie rights.
"The book has done what we wanted it to do, which is to be bought by people who are not experts," said Brodo. He added, however, that his discipline will probably continue to attract few professionals.
"It's been hard for people to get jobs as lichenologists," Brodo said. "A lot of amateurs are very good. They're the hope for the future."
Knudsen sees a future in which a specimen of every die-hard lichen in Southern California is identified, preserved and housed in a herbarium like UC Riverside's. He's working toward that goal one boulder and log at a time, scraping away bits of lichens for posterity.
"Buellia sequax," he said, his lens pressed against an outcropping of sandstone in the Santa Monicas. "This is common."
He lumbered up the trail to take in the view toward the north, a maze of green and yellow creases between the mountains, the city hidden behind them.
"One really rare lichen is on that ridge -- Texosporium," Knudsen said, pointing to the distance. "Where the rocks are high, there's just a load of stuff."
He looked around from the cliff top where he stood. "Otherwise, it's what you see here," he said.
Knudsen opened his arms to a hillside of needle-leafed chamise, rolling under a cloud-frilled sky tinged with smog.
There were no lichens.