An Inconvenient Plant

One of the world's rarest plants grows in the Presidio. Plans are under way to save it — and ax thousands of trees in...

A beer bottle cap sails off the porch and glides toward Baker Beach far below. Videogame music and howls of trash talk waft downward, along with the odor of kerosene-doused charcoal briquettes. Not far away, tourists outfitted in oversize helmets befitting tank commanders buzz about the Presidio's myriad roads in mustard-colored go-karts, gawking at the Golden Gate Bridge as the sun slowly dips into the Pacific.

Little do they know that just a few yards away is one of the rarest plants in the world.

In a highly unusual move, Michael Chassé, the Presidio's rare-plants coordinator, has agreed to lead a reporter to the site of the very last genetic individual of the once-abundant Raven's manzanita — a location Presidio officials have long kept cloaked in secrecy.

A tall, wiry man with a ready smile, Chassé is outfitted in a brown fleece, thick green cotton pants, and heavy boots, giving him the appearance of a 40-year-old Boy Scout. He mounts a well-used bicycle and pedals expertly up a series of hills, dodging go-karts and choking on the greasy fumes of passing vehicles before veering off the beaten path. Chassé ditches his bike and ascends the side of the bluff, classifying every last bit of vegetation in sight: There's a bee plant! There's a sticky monkey flower — “and it's blooming!” And there's poison oak. In fact, there's a lot of poison oak.

The path to the manzanita soon begins to resemble a game of high-stakes hopscotch: Leap left at the gaping coyote burrow, right at the sun-bleached can of New Coke, and, when possible, avoid the walls of poison oak on all sides (the hopscotch game is fitting; the plant's namesake, Peter Raven, was a boy when he discovered it). Finally, Chassé vaults into a clearing blessedly free of the ubiquitous poison oak and grins — “Well, here we are.” And yet there seems to be nothing to see. Apparently, when approaching the Raven's manzanita, you don't look up or even maintain eye level. You look down — way down.

The mythical endangered plant you'd hack through the jungle to behold in a Hollywood adventure film would be a 12-foot tiger-striped behemoth with orchid-like flowers as wide as dinner plates and tureen-sized pitchers capable of digesting large rodents.

Raven's manzanita, however, stands roughly shoulder-high to a Barbie doll. Past battles with a fungal pathogen have left it with several unsightly brown patches. Just inches off the ground, its dime-sized, round leaves ripple in the constant Pacific wind while its delicate, pearl-white flowers dangle like inverted wine glasses. Its gnarled red branches are no thicker than pick-up sticks. It's not what you would call … majestic. When viewed from afar, it's rather unremarkable — except for the fact that it's the last of its kind.

Two hundred years ago, the manzanita and other low-lying native plants thrived in the Presidio's sandy dunes. Even in the late 19th century, large trees were as difficult to locate in San Francisco as parking spaces are today; it wasn't until 1883 that Major William Jones initiated the planting of the Presidio's 100,000 trees. It wasn't aesthetically motivated: The tall, heavily wooded stands of Monterey pine, Monterey cypress, and blue gum eucalyptus would, Jones declared, “make the contrast from the city seem as great as possible, and indirectly accentuate the idea of the power of the government.” They also obscured the base's big guns.

For the sun-loving manzanita and its ilk, however, the trees were essentially a death sentence.

But now scientists and preservationists like Chassé hope to restore the Raven's manzanita and other native plants in the park to their previous glory. How? In large part, by axing thousands of tall, nonnative trees on 75 of the park's 1,480 acres.

And there's the rub. For the Presidio's most vocal neighbors and aficionados, beauty is only bark-deep. The park management's 30-year, $23 million plan calling for the removal of the trees in favor of dune restoration benefiting dozens of small, threatened plants has touched off a war on the former military base. In San Francisco, you can landmark a “historic tree” — but no one has ever thought to designate a historic bush. Maybe that's because city dwellers tend to be more emotionally attached to trees (some scientists, in fact, ponder whether humans' love of trees is hard-wired into our collective memories from the days we swung from them). In any event, local tree lovers opposed to thinning the Presidio's forests have gone so far as to accuse restorationists of carrying on the work of the Nazis.

Meanwhile, even ardent advocates of Raven's manzanita admit its long-term recovery is a long shot: No plant species has yet been revived from its last genetic individual.

So, if the last Raven's manzanita falls in the forest, would San Franciscans make a noise?

These days, a boy as obsessed with plants as Peter Raven was would probably have his phone tapped by the Drug Enforcement Administration. In 1951, however, the nation's priorities were different — the Red Menace overwhelmed the green one — and so the 14-year-old spent hours traipsing about the Presidio collecting samples.

In the years since, Raven's plant obsession has not waned. He has become, according to scientists contacted for this story, “the most revered man in the English-speaking world of botany” or, more concisely, “God.” Securing a 20-minute phone interview with Raven, now the director of the Missouri Botanical Garden in St. Louis, required more than a dozen phone calls and e-mails to several assistants — and the minute the 71-year-old hung up the phone, he hopped a flight to Israel for a members-only botanical garden tour of the herbage of the Holy Land.

But with all of his accolades (and, it seems, deification), Raven knows you never forget your first species.

“It was a cool, sunny day like you often get in winter,” he recalls. “I would head into the Presidio on weekends, looking for plants. I would come in at Baker Beach and collect on the bluffs. And I went up the hillside — and there was this plant. I knew it was a manzanita, but I didn't expect to see a manzanita there of any kind. People know the distribution of things pretty well, and manzanitas just weren't known there.”


Yet it turned out the plant Raven had just stumbled across wouldn't be known anywhere else. The generations of ecologists and gardeners who have tended the manzanita “mother plant” — which is estimated to be more than 100 years old — since Raven's discovery have been won over by its sheer tenacity. While its forebears couldn't survive San Francisco's housing boom in the 20th century, the final bush is a plant that knows how to cheat death.

In 1958, oblivious Army landscapers undertaking a construction project halted their bulldozers only 20 yards from the manzanita. Thirty years later, a crew of Army lumberjacks felling large pines shading the mother plant nearly landed a tree on it. In rainy years, the plant develops a fungal infection called black smut that often kills 40 percent of its leaves and branches. And, in 1999 and 2000, it was swarmed by hordes of ravenous insects.

“It was like, 'Aaaaaah! The Raven's manzanita is being attacked!'” recalls Kirra Swenerton, the seed ecologist at the Presidio's native plant nursery.

When a horde of tussock moth caterpillars descended upon the plant not long ago, frenzied Presidio employees were relegated to picking off every last one by hand. “There's just the one [manzanita] left, and it's so vulnerable,” Swenerton says. “And for that species to go extinct under our watch, in a national park — I mean, where else would you expect people to take better care of it? Oh, I was freaked out.”

While the mother plant has escaped death, it has hardly lived a fruitful life. No Raven's manzanita seedlings have ever been discovered in the park.

Shortly after the Army nearly bulldozed the plant in 1958, numerous cuttings were taken. These were planted and cultivated into living insurance policies; roughly a dozen “clones” exist within about 100 yards of the mother plant, in addition to specimens at Tilden Park and UC Berkeley. As the name indicates, clones are genetically identical to the original — the sole genetic individual is the mother plant, leaving the species vulnerable to disease and changing conditions. Scientists can replicate Raven's manzanitas like so many photocopies, but without genetic variability a species cannot evolve. In the long run this, too, is a death sentence.

Botanists have long pegged the Raven's manzanita an “obligate outcrosser,” requiring another genetic individual to pollinate it. With none in existence, decades of scientific reports gauged the species' hope of recovery as low.

Still, its champions cop the same attitude as Han Solo careening into an asteroid field: “Never tell me the odds.” Allowing the manzanita to die without a fight would be “like burning down the library without reading the books,” says Holly Forbes, the curator of the University of California's Botanical Garden in Berkeley. “You don't know what you've missed.”

Restorationists like Forbes and Swenerton see the manzanita as “one of the last San Franciscans,” a link to the days when Lieutenant Colonel Juan Bautista de Anza first ambled into the city limits — and got sand in his boots.

Dune restoration in the Presidio is not an abstract concept, but a concrete one. Or, more accurately, it's sand — 70,000 tons of it. This mountain of sand, which was trucked over from the de Young Museum construction site, is roughly the size of a high school gym.

While the sand now sits in the shadow of the abandoned Public Health Service Hospital, a diminutive sign informs those navigating this isolated quadrant of the Presidio that the gargantuan pile is slated to fill a trio of dune restoration sites by 2010. The sign's fluorescent tangerine text also beseeches passersby to stay off the dune — which is, naturally, pockmarked by countless footprints.

While the Presidio's original restoration plan for the Raven's manzanita and other native species called for the removal of 3,800 trees, the version it adopted in 2003 ostensibly goes easier on the chainsaws. And yet the tally of condemned trees is nowhere to be found within the 322 pages of the innocuously titled Recovery Plan for Coastal Plants of the Northern San Francisco Peninsula. Five years after enacting the plan, Presidio officials still aren't sure how many trees will stay and how many will go.

The Presidio is jointly run by both the National Park Service and the Presidio Trust, which means getting answers can be more than a little tedious. National Park Service officials claimed to have no idea how many trees they'll cut. Mark Frey, a Trust ecologist, estimates that perhaps 1,000 or more will be removed from Trust land over the next 30 years. Eyeballing a map, Terri Thomas, the Trust's director of park resources, states that the majority of trees to be cut are on Park Service land — meaning at least 2,000 (and perhaps many more) will go. Most of those trees, Thomas claims, would have died anyway in the coming decades.

The dune restoration plan's methodical pace is difficult to observe in real time, but a few dozen trees here and there add up over the years. The Trust has been removing around 100 trees a year for much of this decade; in 2008 alone, a minimum of 85 trees are scheduled to be felled. NPS spokesman Rich Weideman adds that the parks service's 2010 budgetary request from the federal government will include significant expenditures for tree removal.

That has neighborhood and tree activists grumbling. The notion of removing thousands of trees to provide sunlight for endangered bushes and grasses is as welcome to Presidio neighborhood groups as a family of sand dunes moving in next door.

“I find the nativism movement particularly disturbing, in large part because of its origins in Nazi Germany,” wrote local native plant movement critic Steve Sayad in an e-mail. In a recent online debate with a plant aficionado, Sayad referred to native plant restoration as a “racist and sexist cult” befitting a “Green Nazi.” Several other public critics of tree removal in the Presidio agreed that local native plant enthusiasts' ethos was derived from Nazism.


“Nazis, yeah. That's a term I've heard since day one,” says Peter Brastow, a genial, red-bearded man who looks as if he strolled off a container of Ben & Jerry's ice cream. Now the executive director of the nonprofit Nature in the City, he was Chassé's predecessor at the Presidio, maintaining the Raven's manzanita site for more than a decade. “Nazi and fascist — yeah, I hear those terms a lot.”

For the record, the Nazis were indeed enthusiasts of native plant gardens, and did extol the superiority of German plants. However, they actively sought to “Germanize” the landscapes of neighboring countries — the very opposite of the native plant movement's goal. Also, they killed people.

Certainly, not every critic of native plant restoration will quote the Nuremberg Laws. Yet the neighborhood and tree activists contacted for this story all described the Presidio's plan as an environmental misstep. “Removing trees of any species is pretty questionable these days in terms of global warming,” said Isabel Wade, a founder of Friends of the Urban Forest and executive director of the Neighborhood Parks Council. Added Bill Henslin, cofounder of the antidevelopment group Friends of the Presidio National Park, “So many great old trees, which are good for the environment, are being sacrificed for some arbitrary aesthetic and historical goal.”

These arguments are scientifically questionable. A 2002 study undertaken jointly by Colorado State University and the U.S. Department of Agriculture claimed that some grasses can store nearly twice the carbon that forests can. And a 2006 report by Lawrence Livermore National Laboratory demonstrated that planting trees outside the world's tropical zones actually raises global temperatures. Installing forested tracts over former grasslands — as Jones did 120 years ago in the Presidio — is especially troublesome: Dark forest canopies absorb sunlight, whereas shrubs and grassland reflect it.

But while scientific arguments can be disproved, emotional ones cannot.

“I'm assuming that an environmental argument has more validity than someone's aesthetic preferences,” says Mary McAllister, a former member of the city's Park, Recreation and Open Space Advisory Committee and a public critic of native plant restoration. “But if it's aesthetics you want, I'll tell you that as far as I'm concerned, a forested and landscaped park is a more beautiful place than dune scrub and grassland, which is native to San Francisco.”

As McAllister's view indicates, the fact trees didn't grow in this area naturally is of little concern to their advocates.

“People weren't here naturally either,” says Jocelyn Cohen, a member of the San Francisco Tree Council and the Urban Forest Council. “Nothing that is here now was here then.” In other words, in a city clogged with SUVs, parking lots, and fast-food chains, what's the fuss over some nice trees?

In 2002, while the Presidio plan was being argued, then-Supervisor Leland Yee stepped into the fray with an editorial in The Independent on the unimportance of being native: “How many of us are 'invasive exotics' who have taken root in the San Francisco soil, have thrived and flourished here, and now contribute to the diversity of the wonderful mix that constitutes present-day San Francisco?”

This indignant attitude may form the ultimate irony in today's debate over re-establishing rare native plants such as the Raven's manzanita or sparing the magnificent — though artificial — forests. City dwellers' idea of “nature” is far less likely to be defined by the dunes and brush actually natural to this area, but instead by an imported plantation manufactured to instill awe for higher authority.

“Trees have not only come to symbolize nature to us … they have become a kind of 'second nature' that stands in contrast to the 'first nature' of the original landscape cities have in most cases displaced,” wrote Paul Gobster, a USDA scientist who has authored several papers on San Francisco land-use conflicts.

Gobster reckons the average city resident gives little thought to the merits of native plants in an urban setting. But he's dead sure of this: Once you propose buzz-sawing trees, you'll always have a problem — always. Apparently, it's our second nature to object to the removal of “second nature.”

And while people killing trees can induce general fury, trees killing native plants doesn't seem to bother most folks. “What you're doing when you plant those trees is trapping the fog, which condenses on the leaves and needles and drops as artificial rain, increasing the precipitation by a third,” says Steve Edwards, the director of the Regional Parks Botanic Garden in Berkeley's Tilden Park. “You foster a jungle of blackberries, ivy, and poison oak.”

A strikingly tall and thin man with a long white beard of the sort fashionable in the time of President Rutherford B. Hayes (whom he resembles more than a little), Edwards refers to the nonnative trees shading the Raven's manzanita and other native species as “junk plants.”

“The main things those trees do is reduce the native diversity,” he says. “There would have been, like, 60 types of native plants growing there, maybe 100. And a lot of them are very rare and unique to the site. When you plant those trees, you end up with maybe two or three species. You reduce the uniqueness of California to a homogenized redundancy.”

Statistics back up Edwards' scenario: Fully half of the native San Francisco vegetation listed in the 1958 edition of John Thomas Howell, Peter Raven, and Peter Rubtzoff's A Flora of San Francisco, California has been driven to extinction. When asked whether it's worth clearing out 75 acres of trees to benefit native plants, Edwards seems insulted: “We're talking about a postage stamp of land. It's the least we can do.”

He shakes his head. “The whole of San Francisco was once a floral treasure trove. Can't we do just a little bit? My God!”


At Lobos Creek, restorationists did more than a little bit: Back in 1996, a dozen acres of trees, ballfields, and prime teenager hanging-out areas were bulldozed in favor of rolling dunes dotted with San Francisco lessingia, an endangered native grassy herb.

Karin Hu offers a wan smile as she traverses the gray boardwalk weaving throughout the restored dunes in the extreme southwest corner of the Presidio. For the City College professor, the experience of returning to her childhood haunt is disillusioning in the same way Gertrude Stein was less than enthralled with her old Oakland neighborhood.

At Lobos Creek, there is.there there. The boardwalk sends a clear message: You are here. Nature is there. Hu grew up tromping through these open fields, and believes it played a role in her decision to study animal behavior. If her childhood forays had been restricted to the boardwalk, would her interest have been piqued?

While native-plant advocates have praised the restored dunes as a living museum, Hu feels the description is all too apt: “Museumification” is a much-used pejorative among restoration critics. “This boardwalk has made this area an 'exhibit' — but it's not a good enough exhibit for people to come out and see,” she says. “I see kids out here doing restoration work, and that's great. But are they coming back on their own?”

Indeed, on an utterly gorgeous Sunday during the noontime hour, only four or five other people wandered along the boardwalk — none of them children.

The future dunes — and fenced-off, isolated Raven's manzanita recovery sites — may also be accessible only by narrow boardwalks, if at all. This leaves Hu highly ambivalent.

She isn't alone. Her unlikely kindred spirit is Raven (the man, not the plant). “I had a lot of fun when I was a kid there, wandering around collecting and finding plants,” he says. “Fencing or putting certain areas off-limits is quite all right, but it would be an utter tragedy if it was done on a wide scale and kids don't have contact with nature. Putting aside a bigger area and keeping people out of it is kind of problematic.”

Raven laments that children are no longer allowed to gallivant about the city with nary a care, as he did in the 1940s and '50s. But he grew truly agitated at the notion of natural areas being taken away from them. City kids need to know that nature isn't something accessible only after three hours on a bus. It's all around them and they should revel in it. Besides, if Raven had stuck to the path as a 14-year-old, he would never have discovered his manzanita in the first place.

So, paradoxically enough, converting San Francisco to a more “natural” state may actually make nature less accessible for its residents — and since it will require a maniacal amount of scientific, political, and administrative effort, it certainly won't come about naturally.

After half a century of merely keeping the Raven's manzanita alive, its recovery strategy has shifted into reproduction. In recent years, researchers have uncorked the biggest breakthrough in the plant's history since Peter Raven discovered it on the bluff — at times, however, in spite of themselves.

In 1994, UC Berkeley officials lent the only copy of their detailed research history on the plant to an undergraduate — who promptly lost it. Fourteen years later, garden curator Forbes is still visibly perturbed. But she doesn't need papers to remind her that, in 1995, she led an effort to harvest seed fruits from Raven's manzanitas. She and others plied 4,500 of them with 32 different treatments, including smoke and even sulfuric acid, meant to break the seeds' nigh-impenetrable coating.

For all that travail, 12 plants were germinated. Some of Forbes' seedlings, tall and upright, were obviously the herbal equivalent of the milkman's kids. But others certainly looked like Raven's manzanita. Could all the scientists have been wrong to peg the plant an obligate outcrosser? Could the manzanita have self-pollinated?

In 2004, San Francisco State biology professor Tom Parker commenced genetic testing on the six surviving UC Berkeley seedlings. Parker and technician Craig Reading wrapped up lab work at SFSU's Conservation Genetics Laboratory only this month. And Parker has concluded that three or possibly four of the UC Berkeley plants are 100 percent Raven's manzanita. The population of genetic individuals has suddenly quadrupled (or quintupled).

“Twenty years ago, if you'd have asked me about a single individual of an outcrossing plant and what to do about it, I'd have said you're wasting your money, man,” says Parker, a friendly, middle-aged man in no way related to Elvis' former manager of the same name. “The plant was at the literal edge of extinction, and now it has been moved away from that. There's a lot of satisfaction there, I think.”

The Presidio has invited every last person who has ever worked on the mother manzanita plant to a June pow-wow to discuss what comes next. You would think Parker's revelations would have the scientists turning cartwheels. But you'd be wrong.

“We'll all get in this room and talk and we might be arguing if this is the best use of our time and resources,” Swenerton says. “Can we bring this plant back to a level where it will do well on its own? I don't think so.”

With one plant or five, the gene pool for the Raven's manzanita is barely moist. If extinction can come in a form as mundane as a caterpillar, how can the plant evolve to cope with global warming?

Parker sees things differently. “If the plant has selfed [self-pollinated], then it's never too late.” At a recent PowerPoint demonstration, he walked the audience through his slicing and dicing of multiple gametes and alleles, illustrating his work with a branching chart resembling a thrice-worked-over NCAA bracket. Heads nodded as Parker predicted a future in which sexually reproducing Raven's manzanitas are once again nestled in San Francisco's rocky hills.


And then Parker made his next suggestion: As soon as you have a viable population, flip your lighter and burn them all.

“Nobody likes to hear that,” he explains. “But the only way they reproduce is for the seeds to be stimulated by chemicals from smoke. That's their normal way of doing things.” Padlocking the Presidio Fire Department's doors during an electrical storm could do wonders for the Raven's manzanita, he notes, only half-seriously.

For obvious reasons, wildfires are not encouraged in the Presidio, nor is the wanton immolation of rare plants. So, it seems the species will always be tied to humans, reproducing only when and where it sees fit — and that's if scientists are lucky enough to establish viable populations.

Back atop the bluff, Chassé shivers in the howling wind and peeks down at the manzanita, which is illuminated by the last rays of the setting sun. “It's a symbol, and as the last of its kind, it's a powerful symbol,” he says. “It's a symbol of saving an ancient species and hope for the future.”

Night fell, and Chassé hopscotched the poison oak in semidarkness. He mounted his bicycle again and pedaled home. Almost imperceptibly, the mother plant continued to quake in the wind. It had, improbably enough, survived one more day.

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