City Park Self-Guided Tour – What Tree Where

Mystery of the Elms: Chalk bark and others

So many names for the same tree?

On the Fort Collins City Park Self-Guided Tree Tour Map, E23 is listed as the chalk bark Elm. When I googled this, I found very few entries. Instead, a chalk bark maple, the lace bark elm, and references to a Japanese elm popped up. After I got smart and googled the tree’s Latin name, Ulmus propinqua, the Emerald Sunshine elm showed up even though the Latin name for that tree appears to be Ulmus davidiana var. japonica. There is another tree, the David elm, with that very same Latin moniker. What is going on?

The Chalk bark elm near across from Sheldon Lake

The chalkbark elm makes a brief appearance in Dirr and Warren’s The Tree Book,* where part of the mystery of the disappearing elm was cleared up. According to the authors, both GRIN and The Flora of China have regrouped at least four species of Asian elms, considering them to be one species, Ulmus davidiana, or the David elm. Included in this new grouping are what were once known as the chalkbark elm, the David elm, the Japanese elm, and the Wilson elm. Emerald Sunshine, a cultivar, was derived from the chalk bark elm and seems to be discussed under the name U. propinqua JFA-Bieberich. This tree, included in the Tree for Seattle list, is said to grow to a height of 35 feet with a spread of 25 feet and is pest resistant.

To confuse matters, other sources list Ulmus propinqua/Ulmus davidiana var. japonica as the Japanese elm. Another source states Japanese elms include 6 genera and 35 species. According to them, Ulmus davidiana var japonica is the most resistant to Dutch elm disease. Dirr and Warren* state the oldest Japanese elm (Ulmus japonica, now considered U. davidiana var japonica) in the US was planted in 1890 on the campus of UMass Amherst. They also mention this cultivar is known as Discovery “in the trade,” and both Discovery and Emerald Sunshine are listed under the cultivars under the David Elm. I’m not sure if this says we have three of the same tree species in our arboretum or if all three are so closely related they might as well be the same? Most sources also mention Discovery is highly resistant to Dutch Elm Disease.

What does seem to be true is that many cultivars of Asian elms have some defense against the pests that devastated the American elm. Some of the other traits of these trees, such as smaller size or a more upright trunk with less branching, may make them better choices for yards and roadways.

The Siberian elm showing where a recent large branch was lost to a snow storm in April

One type of elm which is usually not recommended is the Siberian Elm (Ulmus pumila.) You can read more about that species on the USDA plant page where it is stated this elm is invasive in New Mexico. It also mentions it is a brittle tree subject to breakage. For a period of time some friends had the National Champion Siberian Elm in their front yard, but a storm about ten years ago broke enough branches it was demoted. With a more recent storm, its size has probably been further diminished. It is possible**, though, that this same tree was still the #2 Siberian elm in the state of Colorado in 2018. The current champion is in the state of Utah.

The Discovery Elm is in the group of trees West of Sheldon Drive and North of Mulberry while one of the two David Elms on the tour is near the entry to the swimming pool. The Chalkbark elm is near the reservable shelter across from the lake and is one of the smaller deciduous trees in that area. The Siberian Elm is not part of the tree tour in the park.

*Diff, Michael A. and Warren, Keith S., The Tree Book: Superior Selections for Landscapes, Streetscapes, and Gardens. Timber Press, 2019

**The champion trees are listed only by city so it is difficult to know for certain if this is the same tree.

Arborvitae; The Tree of Life or at Least One of Them!

What do Harry Potter and Arborvitae have in common?

I swear I never heard of Arborvitae until this year, but when I stop to think about it, I believe we had some growing in our front yard until we took them out to change the landscape. They were annoying. The branches bent under heavy snow or ice. Arborvitae are native to the eastern United States and Canada where they may be called Eastern White Cedar or Northern White Cedar.

Arborvitae means tree of life in Latin, but unfortunately, in common parlance, other varieties of trees are referred to as the tree of life. The baobab and coconut both may carry that appellation while a specific mesquite tree in Bahrain also is called that.

Thuja occidentalis may have been the first specimen tree to be transported and transplanted to Europe and has been grown there since the 1500s. It was given the name Tree of Life when Jacques Cartier learned from the Iroquois that a tea made from its leaves would cure his men of scurvy. There are five species in the genus, but only two of them are native to North America. The other three species are native to Asia.

Native Americans not only used the leaves for the nourishing tea, but as bedding, and the lumber was used as canoe frames. Many parts of the tree were used for other medicinal purposes, including as an abortifacient. Log cabins have been built from larger specimens, partly due to the wood’s insulating properties and rot resistance. This last property also contributes to the wood’s use as fence posts. Arborvitae are important for wildlife as both a food source and shelter.

Although today this species is most often used in the landscape, it can be a long-lived tree with one of the oldest known thought to be over 1000 years. The Wintergreen Arborvitae variety seems especially well suited as a privacy screen while other varieties planted in a row are used for windbreaks.

P1110617 — A lone Wintergreen Arbor Vitae

According to some sources, the tree has antibacterial, anti-fungal, and anti-viral components. Alternative medicine practitioners may suggest its use during radiation. An essential oil is made from its steam distillate, which is most commonly used to burn off warts. According to the site cited above, the essential oil is up to 65% thujone, Thujone, also a component of absinthe, is considered toxic and the use of the oil, especially ingested, is not recommended. Apparently thujone is mentioned in at least one of the Harry Potter books and caused quite a stir with the religious right!

Two of the three arborvitae in City Park are near each other. A94 Wintergreen Arborvitae (Thuja occidentalis Hertz Wintergreen ) and B96 Techny Arborvitae (Thuja occidentalis Techny) are located along Roosevelt Drive between Oak Street and City Park Drive. Both are in the field on the east side, across from the trolley station and tennis courts. The Wintergreen Arborvitae is closer to City Park Drive, near the tall conifers. The Techny is directly across from the trolley station.

The third tree, E62 Brandon Arborvitae (Thuja occidentalis Brandon) is between the ditch and the miniature Train Station, just past the rock wall that runs along City Park Drive, across from Tico’s.

P1150010 — Close up for the leaves on Thuja.

P1150001_2 — The leaves of the three Arborvitae in City Park

Eat your Redbud

Who knew the Redbud is both beautiful and edible, too?

P4100045a — Blooming Redbud near a City Park exit

Ceres canadensis, the Eastern Redbud, is not native to Colorado. The native distribution is, as you probably guessed, the eastern half of the continent. As this map shows one of the western boundaries to be Nebraska, it might not be surprising that the many trees planted in Fort Collins appear to be hardy if planted in an appropriate spot. In spring the twigs and branches are covered with small red buds without any leaves. The buds then flower with petals colored from red to fuchsia. Some mentions of lavender are also made. When leaves appear, they are heart-shaped. The twists and turns of the branches give the Redbud a distinctly spreading, artistic form. An alternate name for the tree is The Judas Tree.

Redbuds, like the Soapberry and the Kentucky Coffeetree, are in the pea family. Similarly to the Soapberry, saponins are mentioned when discussing the ediblity of parts of the Redbud. Most sources do not suggest any parts are poisonous. Surprisingly, websites mention the buds and flowers can be used in salads or even added to cupcakes! There are a number of videos on youtube about using the flowers and other parts of the tree as food. Another idea is pickling the buds to end up with a product similar to a caper. The fresh seed pods may also be edible. Other uses for this understory tree include using the red roots for a dye. The bark can be used to make an astringent tea for medicinal purposes. Native Americans were reported to use a tea of the bark as a whooping cough cure. The roots, too, were used to concoct cures for various ailments according the the USDA’s webpage.

Although spectacular as the earliest blooming tree in spring, the redbud has visual interest throughout the year. We’ll plan to add some photos of seasonal interest. I also hope to report on the taste of the flowers and buds next spring. Luckily, I have a small example of this tree in my yard. Unfortunately, it doesn’t seem to be much of a bloomer, producing but a few buds and flowers each year.

The tagged tree is E117 on the Self-Guided Tour list.

PA080001 The trunk of this specimen is split with a fungus growing up the gash in the tree. To find it, start at the corner of Jackson and Oak. You could park in the fourth or fifth parking slot on Oak and walk south toward the diagonal road a few yards. It is the largest of the smaller understory trees in that corner of the park. The split trunk is east facing.

Although this is the only identified Redbud on the map, there are others in the park. It took quite a bit of staring at the map for me to figure out that the Redbuds seen at the top of the page are not the identified tree. The one featured blooming in the photo above is very close to the stone wall. The tagged tree is bit southwest and is a much larger version.

If you were to walk along City Park Drive (the one-way diagonal road running east-west) to the intersection of Sheldon Drive, you would encounter two other large older redbuds and their spreading branches. These have long been two of my favorite trees in the park.

Redbuds at the intersection of Sheldon and City Park Drives — Redbuds at the intersection of Sheldon and City Park Drive