Man: "I need an ambulance; a guy here is hurt."
Operator: "What is your location?"
Man: "I'm on Eucalyptus Street."
Operator: "Please spell that for me?"
Man: (long pause)
Operator: "Sir? Sir? Are you there?"
Man: "I'm just gonna drag him over to Maple Street. Call you right back."
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| eucalyptus, Eucalyptus globulus |
Walking the Presidio in San Francisco in November, I smelled the distinctive tang of eucalyptus in the breeze. It evoked good memories of my graduate school days at Berkeley.
That is eucalyptus' contradiction in California. It is an exotic, invasive species that many people are fond of.
(This blog is about Eucalyptus globulus in the Bay Area. There are other Eucalyptus species in California and different issues farther south,)
When California was discovered by Europeans in the 1500s, the coast was thick with trees, redwoods (Sequoia sempervirens) were the standout, but also bigleaf maples (Acer macrophyllum), California bay (Umbellularia californica), and others. The Europeans cut trees for building, and, in particular, for repairing sailing ships. This deforestation gained momentum, and when the 1849 Gold Rush made San Francisco a hub of activity, the hillsides were stripped and timber became hard to find.
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| eucalyptus |
Eucalyptus is a huge genus of plants--over 700 species--in the myrtle family, Myrtaceae. Eucalypts are native only to Australia, plus a couple species found on islands just north of Australia. Europeans visiting Australia immediately carried eucalypts across the world. Entrepreneurs told Californians that eucaltypts were very fast-growing, grew tall and straight, and would make excellent wood for the building needs of northern California. Eucalyptus globulus was chosen and in the late 1800s into the early 20th century, millions were planted. They grew tall rapidly. But, when eagerly cut down, it was a terrible disappointment. By eucalyptus standards, those were young trees. Young eucalyptus wood is not particularly strong and warps and twists as it dries. It also expands and contracts with the weather more than most woods, which is tricky in a building and terrible on a ship. Old trees (75 years old or older) can make good wood for building. Despite many attempts to find uses for the vast planatations of eucalyptus in northern California, they have mainly been left growing.
From the tree's point of view, being "useless" is wonderful; they get to stay on the hills, not be cut down. Making the fine tall trees of today.
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| Eucalyptus globulus, eucalyptus |
Forests, including forests of exotics if your natives have been logged, are generally a good thing. Eucalyptus globulus, though, burns easily. The oils in the leaves are quite flammable. and the big fallen leaves and the bark the trees slough off form an easily-ignited litter. For eucalyptus, that is fine; the roots will resprout after the fire kills competing plants. For residents of the area, the trees are a hazard. (Its not all the fault of eucaltypts, however; historically, redwood forests and California grasslands burned.)
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| Eucalyptus litter |
Eucalyptus is also characterized as invasive. In northern California, it is usually too dry for Eucalyptus globulus seeds to germinate and the seedlings to survive. However, the trees sprout readily from their roots, creating thickets. The roots can grow under a two-lane road, to colonize the other side. Eucalyptus doesn't spread particularly fast, but it spreads.
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| Eucalyptus globulus seed pods |
Eucalyptus groves tend to be low in plant and animal diversity. The canopy blocks the sun, the chemicals in the leaves are somewhat toxic to other plants, and the tree roots compete for water; few plants survive there. In addition, most California organisms can't eat eucalypts. In Australia, the trees have dozens of enemies--from viruses to koalas--that ate the leaves or the wood or the flowers and seeds. Virtually all of those were left behind in Australia, so the plant grows particularly well--uneaten, unparasitized--in California The space it expands into--and the space it was given when planted--is space taken from natives species.
Again, eucalypts would say, "Sounds like California is a lovely place to grow!"
That freedom from attack is starting to change. At least 18 Australian insects have been captured on E. globulus in California. And eventually some North American species will add eucalypts to their diets. They have only had 150 years to adapt to it so far. But big stands of Eucalyptus globulus are feast tables if you can digest them, and some plant-eating species will evolve to take advantage of that.
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| Eucalyptus globulus on a San Francisco hillside |
Eucalypts grow well in coastal California but are not tolerant of much frost (USDA Hardiness Zones 8-11 only), so we don't see them in Colorado or New York. A dyer in Melbourne praised a eucalyptus tree (not E. globulus) for natural dyes, and I had to tell her there were no eucalyptus within hundreds of miles of my home. I remember it as a clear example that plants that are common in one place may be so uncommon as to be unknown in another. Without traveling, I'd probably not know what a eucalyptus is.
Meanwhile, as California eucalyptus fans point out, they have been in California since before anyone living today was born. People have grown up with them as common trees. They represent "home" or California--or both--to many people. Other people marshal the downsides listed above and wish them gone. The argument is a good example of the debates over what plants to grow in our landscapes. Even if you want just natives, is 1492 the proper starting point? Some plants came across the Bering Strait with the Native Americans and the bison. Some plants were carried from their origin all over the Americas in pre-Columbian times. Some plants have evolved significantly in the 400 years since Europeans brought them to North America. And, then there's the plant's point of view: the eucalpytus says, "You humans brought me here; I didn't volunteer. What I did was to flourish where I was planted, like you wanted! Humans are so fickle!"
Love them or hate them, Eucalyptus globulus will be common in the Bay Area for the foreseeable future.
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And so, are suitable subjects for jokes:
What did the hedge say after the gardener trimmed it?
"Eucalyptus!"
Comments and corrections welcome.
References
National Park Service. Early history of the California coast. National Park Service. link (Accessed 1/13/22).
Paine, T. D. Paine, J. G. Millar, and K. M. Daane 2010. Accumulation of Pest Insects on Eucalyptus in California: Random Process or Smoking Gun? Journal of Economic Entomology, 103 (6): 1943–1949, link
Rowland, T. 2011. How the Eucalyptus came to California. A cautionary tale. Santa Barbara Independent. Jan. 15, 2011. link (Accessed 1/15/22).
Kathy Keeler, A Wandering Botanist
More at awanderingbotanist.com
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