If you smell like a cough drop when you stumble out of the California woods, it’s because 100 of the world’s 600 species of eucalyptus grow there. None is native. They were imported from Australia during the second half of the 19th century as we were hawking our redwoods to the Aussies. “Wonder trees,” the eucs were called, because they shot up in coastal scrub and vast redwood clearcuts.Distillation from their pungent, oily leaves rivaled Dr. Kickapoo’s Elixir for Rheum, Ague, Blindness, and Insanity. Eucalyptus was said to relieve pain, irritation, insomnia, malaria, venereal disease, bladder infections, cystitis, diphtheria, typhoid, dysentery, and the “fetid smell of gangrenous limbs.”Eucs were planted with varying success across America, but they took off in California. In 1876 Ellwood Cooper planted 50,000 euc seedlings on his ranch near Santa Barbara. Three years later they were more than 40 feet high; 32 years after that they were 175 feet high. Blue gum, the most popular imported euc, was unleashed in 1853. By the 1870s it was a dominant feature in California’s coastal and central landscapes. Groves doubled in area every decade. “Eucalyptus trees are being planted all over the bare foothills of southern California,” effused Harry W. Dunn in 1906. Fueling the craze in the early 20th century was a statewide seedling-giveaway program run by the University of California Experiment Station. Speculators jammed eucalyptus seedlings into cutover land and then sold the property for huge profits.In Australia durable euc lumber had been milled from old growth. But in America the young, water-swilling euc pioneers were stuffed with sapwood. The few boards they yielded cracked when seasoned. Eucalyptus railroad ties threw their tracks. Soon eucs were being sold only as firewood, sometimes for just $1 per cord. As they continued to spread and grow, their thirsty roots blocked drains, tore up pavement, damaged foundations, and fueled wildfires.Of the many eucalyptus species that evolved with fire, none is more incendiary than blue gum. “Gasoline trees,” firefighters call them. Fire doesn’t kill blue gums. Rather, they depend on fire to open their seedpods and clear out the competition. And they promote fire with their prolific combustible oil, copious litter, and long shreds of hanging bark designed to carry flames to the crowns. Blue gum eucalyptus doesn’t just burn, it explodes, sending firebrands and seeds shooting hundreds of feet in all directions. Living next to one of these trees is like living next to a fireworks factory staffed by chain-smokers.What are the costs of America’s infatuation with the eucalyptus? And have we learned anything from it? My search for answers took me to Bolinas, California (population 1,500), an hour north of San Francisco at the end of a mountain road that threads along bare, fogbound headlands. On a bright October morning Geoff Geupel, terrestrial program director for the Point Reyes Bird Observatory (PRBO), led me through a grazing lease and down to Jack’s Creek, in Point Reyes National Seashore. Blue gum eucs towered to the west and east, long, leathery leaves drooping earthward, trunks light brown–almost white in spots–and looking as if they had flirted with a debarker.Between the euc groves, in the dry creekbed, grew some of the last coastal scrub in Marin County, a profusion of plants that belong here and are all vital to wildlife–coast live oak, California bay laurel, monkey flower, coyote bush, wax myrtle, California sagebrush, lizard tail, mule’s ear, cow parsnip, willows, native bunchgrasses. The scrub had its own gray, understated beauty, a beauty largely unnoticed by the public. Coastal scrub never had a Joyce Kilmer to write sappy verse about it. Trees don’t belong on this riparian corridor or on most of the surrounding hills or, for that matter, in most of earth’s terrestrial ecosystems. When the Boy Scouts started cluster-bombing Marin County with seedlings, Ansel Adams helped run them out, declaring, “I cannot think of a more tasteless undertaking than to plant trees in a naturally treeless area, and to impose an interpretation of natural beauty on a great landscape that is charged with beauty and wonder, and the excellence of eternity.”Geupel pointed out the rustling, fleeting forms of birds and called my attention to their vocalizations, most of them strange to my Yankee ears–the churring of wrentits; the quiet tseet of bushtits; the high, thin whistle of golden-crowned kinglets; the clicking of ruby-crowned kinglets; the metallic chink of California towees; the bossy flocking notes of white-crowned sparrows; the oh dear me of golden-crowned sparrows, fresh in from t he Arctic and so full of blarney that they didn’t know they weren’t supposed to sing in autumn. In winter a resident race of white-crowned sparrows, rufous-crowned sparrows, and Bewick’s wrens (all declining) forage for insects in the green leaves of live oaks, wax myrtle, and bay. They breed here, too.In the eucalyptus grove to the west we met perfect silence, a scene from Keats’s “La Belle Dame Sans Merci” in which the “sedge is wither’d from the lake and no birds sing.” The eucs, I suppose, were beautiful in one sense, but their beauty struck me as cold and otherworldly, the beauty of the hollow-bodied fairy dame who sat sideways on the knight’s horse before sucking out his youth. The aliens had sucked out the creek. As eucs’ trunks move in the wind, their sinuous roots tear up huge chunks of earth that slide into the channel. A quarter-mile seaward they literally spill onto a beach strewn with their bleached carcasses. Trees totter on a high bluff, then fall, taking more topsoil with them.Â The only native plants we encountered in the grove were shallow-rooted–mostly poison oak. I stuck my hand in euc leaf and bark litter and couldn’t find the bottom; in California it can be four feet thick because the microbes and insects that eat it are in Australia. Native plants that manage to push through the litter often get poisoned; as a natural defense against competition, eucs exude their own herbicide, creating what botanists call “eucalyptus desolation.” Plants that are most immune include poison oak and pernicious aliens such as Cape ivy and English ivy.Eventually we heard a single ruby-crowned kinglet. Native birds do use eucalyptus groves, though the Point Reyes observatory has found that species diversity there drops by at least 70 percent. Eucs flower in winter, attracting insects and insectivorous birds. To deal with the sticky gum, Australian honeyeaters and leaf gleaners have evolved long bills. North American leaf gleaners such as kinglets, vireos, and wood warblers have not; so the gum clogs their faces, bills, and nares, eventually suffocating them or causing them to starve.Bird carcasses last only a few hours in the wild; if you find a few, it probably means that lots of others died, too. One local bird author I talked to–Rich Stallcup, who writes for the PRBO–told me that over the years he has found about 300 moribund warblers “with eucalyptus glue all over their faces.” Says Stallcup, “We see a large number of gummed-up Townsend’s warblers, yellow-rumped warblers, ruby-crowned kinglets, Anna’s and Allen’s hummingbirds, and a few Bullock’s orioles. Anyone who birds around eucalyptus trees sees it all the time.”Bird artist and birder Keith Hansen, who illustrates some of Stallcup’s work, has found about 200 victims. “The worst one was last year–a yellow-rump,” he says. “At first I thought it was deformed, because there was such a dome of gum over its beak that it made a horn. The bird was hunched forward, breathing very heavily.” If you try to remove the gum, the upper mandible will break off in your fingers.Gum isn’t the only danger. Eucs give nesting birds a false sense of security, creating population sinks. For example, the PRBO has found that in eucs, 50 percent of the Anna’s hummingbird nests are shaken out by the wind. In native vegetation the figure is 10 percent. “Birds will use these trees year after year, nesting but producing almost no young, until the population crashes,” says Geupel. Somehow the public isn’t getting the message about America’s largest weed. After the PRBO published a Stallcup-Hansen article entitled “Deadly Eucalyptus,” the group got a call from a woman asking what kind of eucs she could plant that were good for birds.