Tree Talk: Eucalyptus — making its way north
Along with kangaroos, koala bears and Nicole Kidman, list eucalyptus as one of the great gifts from Australia to the world. Nearly all the 800 species of this remarkable genus are native to The Great Down Under.
Eucalyptus gets its layman’s moniker, gum tree, from the thick, gummy sap that oozes from the trunk if wounded. Eucalyptus can be found as trees with a wide variety of mature heights and also as shrubs. You may have bought the juvenile foliage, which is harvested and sold in flower shops. The leaves are the food of koala bears (these adorable marsupials are not really bears, but given their cuddly, cute looks, the nickname makes sense).
Most eucalyptus have distinctive and fragrant leaves, roundish or lance-shaped, leathery and in shades of green, blue green and even slivery gray. The trees bloom with interesting flowers turning into highly ornamental seed pods. The bark of the plants is showy, an assortment of colors revealed as the bark peels off. In short, this family of plants is as varied and interesting as the continent from which it comes.
The more gigantic species of the eucalyptus genus stand, along with coast redwoods and Douglas firs, among the world’s tallest trees. The Guinness Book of World Records tells us that the tallest tree ever measured was a eucalyptus regnans, which towered 435 feet to a broken top. It likely topped out at over 500 feet in its prime.
First introduced to California in 1856, eucalyptus quickly adapted and swept into the mid-19th century horticultural community. It was planted and replanted until most Californians have come to think it is native. In the early 1990s, intrepid gardeners began experimenting with species they thought might be hardy here, and eucalyptus began migrating north and appearing in Seattle gardens.
The first to be introduced was E. gunnii, listed to be hardy to 5 degrees Fahrenheit. Then came E. pauciflora niphophila, which is 5 degrees more-cold tolerant and beloved for its smooth white bark and silvery blue, lance shaped leaves. One success led to another, and the eucalyptus plant palette grew.
Gambling on hardiness, our gardeners discovered more cold tolerant species. Thus, eucalyptus is no longer a rarity in our area. In his iconic book “Trees of Seattle,” Arthur Lee Jacobson devotes five pages to eucalyptus, naming over 40 plants he has inventoried around Seattle and 26 species that he implies are reliably hardy here. With book in hand, I set out to find a number of them, all surprisingly robust and healthy, among them the three species Jacobson says are the most-cold tolerant: Eucalyptus gunnii (cider gum), E. pauciflora (snow gum) and E. perriniana (spinning gum).
Strolling the three blocks of East Lynn Street (north of East Madison Street), midway, you’ll come to an alley on the south side. There, you’ll see a meticulously managed tree, at the edge of an impeccably groomed garden. It gives eucalyptus a new twist — literally.
About 20 years ago, owner Christa Philipp and her mother returned from a trip to Carmel, California, with three seedling eucalyptus plants, all together in a single one-gallon can (one of an unknown species, two of another). The plants grew in a large pot atop their roof deck, never dropping a leaf in any of our winter cold snaps. About 15 years ago, the trees were taken from the pots and planted in the ground, largely under the care of her husband, Bert Philipp. In a moment of whimsy, the three plants were twisted together, secured and there they stayed, growing as one tree. The result is a handsome horticultural curio with double the impact of interesting bark and leaf forms. The Philipps groom the plant annually, taking out the tallest vertical shoots (some as long as 3 feet in a single year), thinning out cross branches and ones that grow too close together. On a clear day, looking up through the tree to a blue Northwest sky is as visually rich to the sense of sight as the fragrant leaves and bark are arresting to the olfactory nerves. It was suggested to Bert that he lay the bark, which flakes off the tree, on a garden path. Under foot, the crushed bark emits the heady eucalyptus fragrance.
The entwined trees in the photograph continue to be impervious to our winter cold. They show no signs of stress in our coldest temperature dips, and when the branches are weighed down in a heavy snow, once shaken free of snowflakes, the supple branches spring right back.
As for the two species: Arthur Lee Jacobson was stumped (and that’s a rare occurrence). Arthur suspects the large, mottled trunk in the middle of the three belongs to Eucalyptus gunnii, and the two trunks rising on either side, possibly a subspecies of E. pauciflora. Meticulous as he is with plant identification, he came up with a suggestion that was as grounded and down to earth as the best of science: Question and collect data from various sources. “Ask your readers,” Arthur implored me. “See what they come up with. I’ll keep working on it.”
Eucalyptus seem to thrive in our cool, moist, overcast weather. Planted in the fall, allowing them to establish through the winter and spring, they should survive on the water that nature provides. They’ll do best in a sunny spot with good drainage. Check mature heights carefully as you are choosing a planting spot. Many species can get huge. They litter the ground with leaves and bark, so know that if you favor a clean garden, you’ll be raking often.
In the event we do have a monster freeze in future winters and the trees defoliate, don’t rush to cut them down. They are likely to be alive. In December of 1990, when the bay area of California experienced a 150-year freeze, many eucalyptus completely defoliated. I was there. Communities cut them down immediately. It was the wrong thing to do. Quite likely those trees would have sprouted new growth in time. Any dead wood could have been pruned out, and the trees would be standing today. Interestingly, the stumps of most of those truncated trees shot up suckers the following spring. These suckers were selectively thinned and grown into new trees. Often what had been singled-trunked trees returned as multi-trunked plants.
I’m giving thought to adding a snow gum (E. pauciflora niphophila) to my city plot. The form, the bark, the leaves, the scent and the rattle of the foliage in the wind all seem appealing. Furthermore, with all the changes in climate expected, and the fact that even many animal species seem to be migrating around the world, who knows? I might look out into my garden one day and find a koala bear or a kangaroo — or maybe even Nicole Kidman!