Autumn Highlights Tree Tour

The Autumn Highlights Tree Tour:

1. European Larch: The Larix decidua on the path behind the Stevens Way Bus shelter west of Anderson Hall is perhaps a surprising start to a tour of fall colors. Unlike many of its fellow conifers, this gymnosperm (plants whose seeds are unprotected by a fruit or ovary) is not an evergreen, losing its needle-like leaves as the chill of winter begins. Larches are resilient, thriving in some of the coldest regions of the world including boreal forests and high alpine mountains. They have been known to survive in temperatures of as low as -58 degrees Fahrenheit (-50 degrees Celsius), and in such extreme conditions reducing the potential for snow building up on branches is extremely advantageous. It is for this reason that members of the larch family, also called Tamaracks, turn a spectacular orange hew in the fall before dropping their tight whorls of needles. The color on this specimen is fair, but in the high reaches of the Cascade range our native larches steal the show, standing out brightly against the rocks.

2. Bigleaf Maple: Although not at all the showiest of trees in the Maple Family, our native Acer macrophyllum deserves to be mentioned as it is perhaps one of the most abundant (if not the brightest) sources of fall color in our home state. One of just a few maple species native to Washington, colors of this species range from a dull brown to a respectable orange-yellow hew, particularly impressive in pure stands highlighted by dark conifers. As the winner of “largest leaf” prize for the maple family, fall is also a great time to pick up and observe the dinner plate sized palmate leaves of these magnificent trees as they fall to the ground.

3. Sugar Maple: Perhaps one of the best known fall color trees in the United States, Acer saccharum is an emblem of the east and midwest, dominating as a large tree with many endearing traits. A small grove of these trees stands the west side of Rainier Vista, just south of Drumheller Fountain. While winter chills allow these trees ability to produce a delectable sugary sap which may be processed into syrup, the transition from summer to colder days brings a display of red unrivaled by few. Although its fall colors can lean towards the yellow end of the warm spectrum, often they take on a deep crimson hue, the palmate leaves glowing before falling or blowing to the ground in quantities great enough to thrill any lover of a good fall leaf pile. Sugar maples may be distinguished from close relatives by relatively smooth bark, even into older age.

4. Ginkgo: Standing beside the Aerospace Engineering Research Building is a true fossil tree. The ancestors of Ginkgo biloba can be traced back in the fossil record more than 200 million years, and the tree has existed in its current form for the last 60 million. This means the lineage predates angiosperms, the flowering plants that are the most common of today’s deciduous trees. Undeterred by its status as a conifer, which are usually evergreen, the ginkgo proudly sheds its foliage each fall—often all at once—each bright, golden leaf dropping over the period of a single day or two, a truly worthwhile sight to see!

5. Pin Oaks: The deep red hue of Quercus palustris is a common site lining our Seattle streets this season, their name arising from the sharp lobes tapering to graceful points at the tip. Stevens Way between the Mechanical Engineering Building and HUB is one such lucky street. Unlike many of the other autumn leaves on this tour, those of the Pin Oak often remain attached well into winter, long after they have browned, remaining shriveled but in place until a solid wind or the new growth of the next spring removes them from the bare branches.

6. American while elm: The Ulmus americana specimen south of the Husky Union Building is magnificent not just for its bright yellow fall foliage, but also for its tremendous size. Its immense crown ensures that the beautiful autumnal color dominates the background as one looks up the nearby street of oaks, with their lovely contrasting palette of reds and yellows. A native of a large swathe of eastern North America, the tree rarely reach an appreciable size due to Dutch elm disease, which has ravaged the species in the wild since the 1960s. The disease-free UW specimen serves as a reminder of the tree’s beauty and grandeur decades after the loss of so many of its brethren, which once lined streets across the continent.

7. Vine Maple: The second of the three maple species native to Washington, Acer circinatum is distinctly more showy in color than its much larger cousin the Bigleaf Maple. With small palmate leaves, each containing 7-9 toothed lobes, this undergrowth species brightens many forests of the northwest with an array of fiery colors, often varying even on the same tree! Common as a cultivar, vine maples may also be found throughout Seattle gardens, just like this one gracing the west side of the HUB, making up a thrilling part of the autumn experience.

8. Saw-Leaf Zelkova: Zelkova serrata is commonly planted as a street tree, thus there are many streets in the Emerald city graced by the coppery red to yellow hue that this species presents as the days grow shorter. These specimens grow along the Allan Library beside the HUB lawn. The Zelkovas opposite leaves zig-zag down the branch, each toothed on the edge and drooping towards the tip. Each leaf may have a color range, fading first to one hue then another, but delaying the transformation near the pinnate veins in such a way there is a bright spectrum of color, each leaf individual in appearance The saw leaf name is evident on the serrated edges of these beautiful leaves.

9. Dawn Redwood: Another species of deciduous conifer, Metasequoia glyptostroboides is, like the Ginkgo, of an ancient lineage. Whereas the Ginkgo is the last in its family however, this tree is the relative of some of the greats, the Coast Redwood and Giant Sequoia, each some of the largest tree species in the world. Unlike its cousins however, the Dawn Redwood enters fall in a different garb than its summer greens, the needles turning a flaming orange before dropping in strings to the ground, letting the soft winter light reach the red bark that defines the Sequoia genera.

10. Paper birch: Standing at the southeast tip of Thomson Hall, our first Washington native of this tour, Betula papyrifera, is actually a fairly uncommon sight in Seattle compared to its European and Asian cousins. That’s because it is difficult to cultivate this riparian native in a nursery setting. And what a shame that is, for this tree puts on as grand a show as any, with delicate, drooping branches holding buttercup yellow leaves, each rounded, abruptly pointed, and surrounded by fine serrations. The fall color contrasts nicely with the most identifiable feature of the birch—its bright white bark.

11. Copper beech: Not limited to a single season of color, Fagus sylvatica f. purpurea, a European native, is cultivated for its brilliant coppery hue, which persists all through the growing season. The specimen at the northwest edge of the HUB lawn wears an autumn-like garb from the day its leaves emerge in spring. In summer, the metallic, light-bending leaves may seem the epitome of charm, but in autumn they develop an even more vibrant shade, looking like gold coins at the bottom of a fountain—a truly unique hue that’s a must-see on the fall highlights tour.

12. Sugar Maple: We have already seen Acer saccharum on this tour, but the species is no nice we have to show it off twice! A line of these trees graces the street in front of Thomson Hall.

13. Black Walnut: A tree with a broad range from the eastern seaboard to the great plains, Juglans nigra is best known for its edible seeds, and the difficulty of extracting them from their impenetrable shells. In this season however, they shine a bright yellow, their massive compound leaves drooping and releasing as the base of the dark trunk is blanketed by the fallen leaflets.

14. Pignut Hickory: Another bright yellow fall masterpiece is the Carya glabra beside Paccar Hall. A relative of the Black Walnut already seen on this tour, this species matches not only the fall hues but also shares the ability to create edible fruit, the hickory nut. These nuts come ripe in the fall season as well, shedding their husks as the trees compound leaves begin to transition to gold.

15. Northern red oak: The Quercus rubra on the southern end of Denny Field is a monumental specimen by any standard: Its rounded crown covers a third of an acre, with each heavy branch as large as a respectable-sized tree in its own right. In fall, the leaves—as the common name indicates—turning a ruddy color, but the cumulative effect with this particular tree is similar to encountering a bright orange-red circus tent. Another fall feature of oaks is their acorns, and the brown, cup-and-saucer shaped nuts of this species are an important food source for many animals across the tree’s native range in the U.S. Northeast.

16. Silver maple: On Parrington Lawn just south of the Law School stands a maple species native to the eastern and midwestern United States. Acer saccharinum is one of the showiest of the autumn trees on the Brockman tour, with colors ranging from bright yellow to dark red on leaves sporting beautiful ragged edges. The vibrant shades in the crowns and—when the leaves drop—on the grass beneath them strike the eye, and the shaggy bark is notable enough to offer yet another compelling reason to stop and appreciate these fall beauties.

17. Sweetgum: A final tour highlight, this may be a case of “saving the best for last.” Native to the U.S. Southeast, Liquidamber styraciflua has perhaps the most incredible fall color simply due to its inability to settle on just one. The UW’s specimens form a circle at the base of Memorial Way, and even on one single tree you can find a spectrum of color from the purest yellow to the deepest red, plus a mix of everything in between. Sometimes you’ll see this on just one leaf! As the palmate leaves of sweetgum fall to the ground, you can be forgiven for feeling like there is no place better to be than amongst the trees of UW on a cool autumn day.

18. American yellowwood: This specimen of Cladrastis kentukea stands tall in front of the Women's building near Parrington Hall. The species gets its common name from the color of its heartwood, but that isn’t the only thing yellow about the tree this time of year. As we edge towards winter, this member of the Fabaceae (pea family) from the central United States cloaks itself in a brilliant orange-yellow hue, its compound leaves shedding leaflets from a broad, rounded crown. Of note are the large, flat, dangling, yellow-brown seedpods exposed as the leaves drop away, serving as a reminder that this plant is a legume.

19. Quaking Aspen: Perhaps bold to say the best was saved for last, but in the case of the Aspen few trees can compete in terms of fall glory. At the south end of the architecture building grow several Quaking Aspen trees. Populus tremuloides may be found across the country, one of the most widespread trees in the northern hemisphere. While alone their fall color is fair, it is in groves where this species truly shines, turning entire mountains varying shades of yellow, orange, and red. Since aspen reproduces mainly by sending up new growth from existing roots, in many cases entire groves are actually one single organism, all genetically identical and sharing resources through a vast network of roots. Because of this, entire groves often share the same fall color. However, when one patch of hillside is splashed with a large patch of bright red beside a grove in pure yellow, it provides a marvelous means of spotting the difference between two massive and grand organisms, each using its myriad of trunks to put on a spectacular autumn show. If only to make the spectacle even more magnificent, aspens have a flat leaf stalk (or petiole), meaning that even the slightest breeze will send the whole tree shaking as if in a dance, waves of color rolling along as the weather cools.