trees native to Asia – 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.

Silver Linden. A Bee Killer?

Bees are often found dead or stunned underneath the silver linden.

One of the other unique lindens in the park is the Silver Linden (Tilia tomentosa.} This linden, or lime, is native to countries east of the Adriatic Sea, including Albania, Bulgaria,Croatia,Greece,Hungary, North Macedonia,Montenegro,Romania,Serbia, Slovenia,Turkey, and the Ukraine. The tree was introduced into Great Britain where it grows into north Scotland. This source states the tree was used for lumber in Bulgaria and Romania. Another interesting use of the wood is in carvings found in Orthodox Greek temples.

A paper on various species of linden in the Balkans mentions that Tilia tomentosa tends to reproduce via sprouts. This same paper recounts it is possible for some lime trees to live for a thousand years. It does not indicate which of the various species have reached this age, though. The University of Florida suggests propagation of this species is most often accomplished via cuttings as seed germination can take two years.

Oddly, the USDA calls T. tomentosa a native of Ontario. Most likely this is a mistake as most other sources list it as native to Asia and Western Europe exclusively. In North America this variety is hardy in zones 4-7 and was introduced in 1767.

Monumental Trees lists the tallest silver linden, a tree in Belgium, at 121 feet. The US list of Champion trees has no listing for Tilia tomentosa, although many sources, including Dirr and Warren’s The Tree Book:Superior Selections for Landscapes, Streetscapes, and Gardens, say it is an excellent street tree that is more resistant to aphids than other lindens, although other sources dispute this. This may also be true of Japanese beetles. It may be more drought and pollution resistant.This information seems to differ by the state which provides it and leads me to believe its properties vary with the environment it is in.

Heart-shaped, serrated leaves

Serrated leaves of the silver linden.

With the silvery underside to its leaves, many consider this a good shade tree with a shimmery effect in a breeze. Like most other lindens, bees are very attracted to its flowers from late June into July. Dirr and Warren, as well as others, report this might not be a good tree for bees as they are often found dead or stunned underneath them. Bumblebees are more prone to suffer than honey bees. Recently studies have been done to figure out if the problem lies with the biology of the bees or has to do with the flower nectar. The conclusion reported in a Royal Society (2017) article is that further study is needed to determine the cause of death.

E17 Silver linden specimen Tilia tomentosa in City Park is a smaller tree located along the drive to the golf course parking lot. Part of the fire station can be seen in the background of this photo.

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Lacebark Trees–Species of Similarities and Contrasts

While the lacebark elm is easy to transplant, the lacebark pine requires patience.

Although a tropical tree in Australia is known as the lacebark tree, it appears to only grow in hardiness zones 9 and above, limiting its growth to warm coastal areas in the US. Two other species of tree, both from China, come in a lacebark version, the Lacebark Elm (Ulmus parvifolia) and the Lacebark Pine (Pinus bungeana).

The elm version, also known as Chinese elm, has been introduced to much of the midsection of the United States. Although it is considered invasive in some areas, it has also been considered a good alternative to Siberian elms, which are more weedy. According to The Tree Book: Superior Selections for Landscapes, Streetscapes and Gardens (Dirr, Michael and Warren, Keith, 2019) this elm is useful in stressed environments and has been planted in parking lots, streets, and in parks. It is resistant to both Dutch elm disease and the elm leaf beetle as well as black leaf spots. Hardy from zones 5 through 10, it doesn’t drop its leaves until well into winter, and as may be expected from its name, its trunk is a major focal point when the bark exfoliates to reveal multiple colors.

The Tree Book features write-ups on thirteen different cultivars. Another somewhat unusual use of the species is in Bonsai. The leaves may be eaten cooked or raw and are said to have a pleasant taste which imparts freshness to one’s breath.

While Dirr and Warren state the lacebark elm is “easy to transplant and propagate,” they report the lacebark pine grows slowly and requires patience. It was first discovered in China in 1831. Often grown on temple and palace grounds, the tree is revered and in Korea the largest trees are considered national monuments. The species may grow for 200-300 years with the oldest trees closer to 900 years of age. Often in their native habitat they reach heights of 80-100 feet.* In North America this conifer is more likely to grow to 40′ to 50′ and have multiple stems.

This three-needle pine also has bark that exfoliates in irregular pieces, giving it the appearance of a mosaic. It may not start this process until it is ten years old. Colors which may appear include green, purple, white, and grey.

Although it has some resistance to diseases which attack pine trees, its wood is brittle and it may suffer damage in storms. The seeds from this plant are edible but no information has been given on how to prepare them. Turpentine extracted from this species may be used in a number of medicinal remedies, but as this tree is not abundant in the states or easy to grow, it should not be used for these purposes.

Trunk showing some color

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E2 Lacebark pine (Pinus bungeana) is located behind the fire station on Bryan Avenue, along the drive to the parking lot for the forestry department, next to the mugo pine.

To find the lacebark elm (Ulmus parvifolia) E48 head to the parking lot near the ballparks. It is on a peninsula in this parking lot just about halfway between Mountain Ave and Oak Street.

*The Tree Book: Superior Selections for Landscapes, Streetscapes and Gardens (Dirr, Michael and Warren, Keith, 2019)

Catalpa—the Fish Bait Tree

Some consider the long seed pods and large leaves of this tree to be messy

The genus Catalpa contains ten or eleven (North American Trees, 5th Edition) different species of trees. The Chinese variety, Catalpa ovata, which is on the City Park tree tour, is a native of China but has been introduced in the eastern part of North America.

Two species are native to this continent, Catalpa Speciosa and the southern version, Catalpa bignonioides Walt. Even though neither of the other species is tagged in the park, I am going to discuss them because catalpas are one of my favorites. The trees look very similar with their large leaves and long bean-like seed pods. Each also has clusters of flowers, with the native trees blooming earlier with larger blossoms than the Chinese variety.

The Northern Catalpa (C. speciosa) is native to all but eight western states and Florida and has been introduced into Ontario. The Northern Catalpa is the largest of the three trees, normally growing to 60′. The National Champion tree in Indiana is 78′ and with a 81′ crown spread. C. bignonioides, the southern catalpa, has a range which overlaps that of the northern. It can be found in most of the states where the larger tree doesn’t grow as well as in North Dakota. Although the Southern catalpa is normally only 30-40′ in height (The Tree Book, Dirr and Warren, 2019) the champion tree listed in 2017 is not much smaller than its northern counterpart (75′ x 82′).

The moniker fish-bait tree technically applies to the southern variety of this tree, but the catalpa doesn’t want for other names. They include the cigar-tree, Catawba, Indian-bean tree, caterpillar tree, and Western Catalpa, with the Northern and Southern species sometimes sharing the same alternate name.

P6180005 — The developing leaves of the Chinese Catalpa with a few of the seed pods from last year

The wood of the northern tree has been used as railroad ties, trim carpentry, telephone poles, fences, and furniture. The southern catalpa wood has been used for similar purposes, but its most interesting use is in plantations where it is grown to attract the the catalpa sphinx moth, which is used for fish bait! (The Tree Book, Dirr and Warren, 2019).

Bark from C. Bignonioides has been used to treat malaria. Other parts of the plant have been used for medical reasons, including the roots, although the current writeup from the USDA includes a warning in red that the roots of this plant are poisonous! Plants for the Future rates only the Chinese Catalpa as having possible edibility. The USDA does warn that the native trees may be invasive and weedy. Many people complain that the seed pods are messy and many don’t like the large leaves. My feeling is that the larger leaves make them easier to pick up! Even the New York Times took up the case of the catalpa with the story of its spread in the 19th century.

P6180004_01 — Bark of the Chinese catalpa

The Chinese Catalpa is smaller than the native trees. An additional use of its wood is in the making of a traditional Chinese instrument, the Qin.

The Chinese catalpa C 175 in the City Park Arboretum is along Sheldon Drive, just south of the Indian Magic Crabapple on the eastern side of the road, catty corner from the latrine on the west side of the road. The catalpa trees in town seem to leaf out and flower late in the season, so much so that if you own one, you start to worry it has died, yet the Chinese catalpa is even later. It looks quite scraggly even this late in June this year.

P6180003 — The Chinese catalpa in mid June

Ussurian Pear: the Most Cold Hardy of Pear Trees

This pear is hardy to USDA Zone 3!

Like all pears, cherries, apples, and hawthorns, the Ussurian Pear is a member of the Rosaceae or rose family.

The tree, also known as the Harbin pear or Chinese pear, is native to China, Japan, Korea, and the Ussuri river area, which forms a border between Russia and Manchuria. It is the most cold-hardy of the thirty or so pear species and will grow in USDA zone 3.

The seeds for the tree were brought to the United States in 1926 by a professor from South Dakota who gathered them near Harbin China. This date is disputed by the Morton Arboretum, which states their tree was planted in 1922. The pome of this species is said to be small, hard and not particularly delicious although it might improve in flavor after a frost. The amount of sugar the fruit contains varies widely between varieties.

Some sources suggest it might be used for jellies. Although this website lumps the Harbin pear in with other Asian pears, it says the fruit may also have a tenderizing agent, making it good for marinades. In a chat group, another respondent suggested it might be worth trying to make a perry from the fruit.

In any case, the trees take up to eight years to produce fruit (pomes) and may live up to 300 years. The fruit is eaten by small mammals and birds. In the landscape the trees are used as a windbreak or as a specimen tree. Like most pears, Ussurian pears contain a compound that has antibacterial properties and may also serve as a flea and tick deterrent.

The Ussurian pear (Pyrus ussuriensis) in City park was planted in 1993 and had a trunk diameter of 3.5″. To find this tree: if you start at the intersection of Sheldon Drive and City Park and walk from the South East corner in a straight line south and east from the point of the intersection, you would find the tree between the the two playing fields.

Hong Song, Kimchee, Diabetes, and the Korean Pine.

The Korean pine is an important component of the habitat for the Siberian tiger.

OLYMPUS DIGITAL CAMERA As the name implies, this is not a tree native to the United States, although it may be grown here for its ornamental value. The American Conifer Society lists this species, Pinus koraiensis, as native to Korea and Japan. Other sources state it is also native to China and parts of Russia. Some of the musical names this pine is known as around the world are Hong Song, Chosen-goyo and Chosen-matsu.

A World Wildlife site links pine nut trees and their destruction as an important component in the decline of the Siberian (Amur) tiger, which may be extinct in North Korea. The seeds are a food source for both wild boar and deer, prey of the tigers. This same site blames the rising world demand for the lumber from this tree for its illegal logging.

The seeds are a food staple in Asia, and possibly one of few cash crops in parts of Russia. The leaves may be used as a dye. Various parts of the tree also have been used for medicinal purposes, including ear aches and weight loss.

Of interest is the possible satiety value of the seeds from this conifer. Researchers have reported the nuts are high in Pinolenic acid, which may act as an appetite suppressant and also help lower lipid levels. Other studies suggest pine nut oil may have a role in diabetes control. These nuts are also used in Korean cuisine. The nuts, called Jat, are part of a number of dishes, from kimchee to fruit desserts. This website includes links to recipes.

This white pine with its five needles to a bunch, oldest specimen is reported to be at least 629 years old for a tree found in Mongolia. The tallest tree is reported to be just over 157 feet. This tree was found in mountains in the Russia/China/Mongolia area.

A nursery in Canada states its stock is grown from 100 year old Canadian trees, making it sound as if this species could survive in other areas of the world. The site also has a photograph of a standard-sized pine nut compared to a jumbo pistachio. The implication is that this is a fruitful and beneficial tree to grow for your own use. It states the harvesting of the nuts from the cones is an easy but sticky venture. Rhora’s Nut Farm and Nursery reports the trees produce cones starting at about 7 years, with a few producing as early as six. Each cone yields an average of seventy seeds. Korean pines are grown for nut production in many areas of the continent, including Michigan and Ontario.

The Korean Pine, C134, in the City Park Arboretum may be found along Jackson Street, north of the wooden bridge if you are on the sidewalk. If you are driving, it is slightly north of Olive street. A fairly small tree, it undoubtedly was recently planted. The lack of any visible pine cones might help confirm its young age.

Bees at the Bee-Bee Tree

Hundreds of saplings may grow under a female tree.

The Korean Evodia is another tree with a checkered history in North America. The Latin name for this tree included on the City Park Tree Guide is given as Evodia danielli but it appears Tetradium danielli is also used. Other names include Bee tree, Bee-bee tree or bebe tree. Other sources include the name Honey tree and One Hundred Thousand Flower tree. The current USDA map shows it naturalized in Pennsylvania and Ohio, yet many other states are reporting it as having escaped.

Although Pennsylvania has this species on its watch list for invasive potential, at this point it is not known how it might damage the environment. A four-acre patch of escaped trees has been reported in Maryland. A short article published in 2017 gives more information about the nature of this tree and its invasive nature, stating that hundreds of saplings grow under a female tree and it has been seen outcompeting other invasive species such as the tree of heaven and Japanese stilt grass.

First brought to the United States in the early nineteen hundreds, this specimen is native to the Koreas, northwest China and other parts of Asia. Why is it given its various monikers?

Although the many small blooms, in clusters that resemble poorly formed cauliflower heads, are rather high up and hard to see, bees swarm these late bloomers. It is the second week in September here in Colorado and the flowers are still blooming. Purportedly female flowers will turn to stunning red seed pods.

This propensity for late blooming makes the tree popular with both bees and possibly beekeepers. Although many sites mention this as a nectar source, the references I found date to the 1970s with few current citations. One website suggests a substance made from the seeds is used as both a cooking and hair oil!

In the 1990s the US Forest Service lamented this tree was not used more often for ornamental purposes and suggested it would be a good street tree. Similar to the Amur cork tree, parts of Korean evodia have been used in Chinese medicine for 2000 years. It has been used to treat arthritis, headaches, gastric upset, and other ailments. Both WebMD and RxList suggest there is not enough evidence to show if any parts of the plant are effective.WebMD includes a number of drugs with which evodia may interact and cautions pregnant and breastfeeding women from using it. Surgical patients should also use caution as it might interfere with blood clotting.

C185 Korean Evodia (Evodia danielii) is either no longer tagged or the tag is nearly impossible to find when the tree is blooming. At the right time of year, though, it is fairly easy to identify by the many bees buzzing around its flowers and its somewhat unusual shape. If you found the Amur Cork, walk slightly south and west from there. Although not perfectly aligned with Olive Street, you can also start from where Olive Street tees into Jackson and walk west and slightly south across the park to find it. It is near a large evergreen tree.

Amur Cork—Landscape Lovely or Harmful Invader?

First brought to the United States in 1856

Amur cork tree (Phellodendron amurenses) is native to China, Korea, and other areas of Asia. It was first brought to the United States in 1856 and grown in the Harvard Botanic gardens as early as 1908. From 1933 it has been reported to have naturalized in New York. Currently it is considered an invasive plant in a number of states. As an invasive plant it crowds out native trees and produces berries which are less nutritious than the nuts of native trees; its berries do not have the same essential fats needed for wildlife to survive through the winter.

Some of the sources referenced above speculate that the trees were brought from Asia by railroad workers. The trees’ growth patterns have contributed to its “success” in crowding out native specie. By suppressing the growth of canopy trees, it has become one of the dominate trees in eastern states. Although many states warn against planting Amur cork, others suggest Phellodendron amurenses is a good landscape variety. A few suggest only male trees be considered. This might be a reasonable solution in areas were there are no others, but in areas where the trees have naturalized, the male tree may still fertilize female trees and add to the problem.

Possibly one of the reasons Amur Corks were originally brought to North America is that it is considered to be one of the fifty most important herbs used in Chinese medicine. Some of its compounds have been used to treat meningitis, arthritis, cancers, and diseases of the lungs. The Ainu population of Japan also used parts of this tree as a painkiller.

WebMD mentions most of the uses above. It also states some of the trees’ compounds, such as berberine, might lower blood sugar and LDL cholesterol. At the same time they include warnings about possible harmful effects. There is limited scientific research to support usage.

Other non-medicinal uses have been mentioned; older literature suggests the bark as a substitute for cork.

It may be used for cork in Russia. An oil made from seeds may have insecticidal properties. A yellow dye obtained from inner layers of bark, was used to produce yellow-tinted paper, useful in distinguishing the important of various Chinese documents.

The Amur cork tree (C138) may be found in City Park where Olive Street intersects with Jackson Street. As can be seen in the photo at the beginning of this post, the tree is almost directly across from Olive Street street.