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.

Plaque for Largest Siberian Elm

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.

 

 

The Iconic American Elm is Still Hanging Around

An elm which had survived 14 bouts of Dutch Elm Disease was cut down while the 101 year old warden who had cared for it looked on.

The American Elm in Winter

The American elm (Ulmus americana), native to about two-thirds of North America, is an iconic tree and was one of the nominees for the National Tree. Although the oak received this honor, both Massachusetts and North Dakota call American elms their state tree. In the past, elms lined the streets of midwestern cities, college campuses, and the National Mall. The Oval at Colorado State University is still lined with American elms, some of which were planted in the 1880s. Elms dotted the upstate New York campus where I attended undergraduate school. I remember Dr. William Huntley lamenting the death of elms around campus, which might have been brought about by a more deadly strain of Dutch elm disease in the 1960s.*

Autumn color of an American Elm

I’m lucky to have three large elms on my property as the one on the southside tends to keep the house cool in the summer. Once a friend mentioned she considered elms the scrounge of the earth. I was surprised but then remembered the multitudinous seeds, more properly referred to as samaras, covering our sidewalk and how many seedlings I routinely yank out of flowerbeds. Without a doubt they are tenacious trees with a number of deficits, including that surfeit of seed production. 

Elms may also harbor aphids which produce “honeydew,” nearly painting my white house a sticky black. European elm scale also contributes to the annoying honeydew and can debilitate a tree. Another pest, which chews holes through elm leaves, giving them a lacy look, is the elm leaf beetle. My house is now 102 years old, so I assume the trees are about the same age. I would not consider cutting them down unless they were rotten or became infected with Dutch elm disease. According to numerous sources, elms can live up to 175-200 years with an outside age of 300 years. The current oldest tree in the US listed on Monumental Trees, though, is estimated to be no older than 151 years. 

Dutch elm disease started devastating stands of elms in the 1930s after the disease was carried to North America by European furniture makers in the 1920s. Known as a vascular wilt disease it can be transferred in one of two ways. First, native elm bark beetles, as well as European bark beetles, carry the disease-causing fungus. Dutch Elm Disease (DED) can also spread from the roots of closely planted trees. World-wide there are up to forty members of the Ulmaceae family but only six species are native to North America. All are susceptible to Dutch Elm Disease, but American elms are affected in the greatest numbers. Estimates are that 77 million trees  were lost to the disease between its introduction and 1970. Current estimates of loss are closer to 300 million.

American elms (Ulmus americana) do still exist. Plant geneticists have created both American elm clones more resistant to DED, as well as cultivars which may prove to be less susceptible. Possibly the most famous elm tree was one which survived 14 bouts with the disease, thanks to Frank Knight, the tree warden of Yarmouth, Maine. According to the Liberty Tree Society, this elm was planted in the 1770s. Mr. Knight spent fifty years tending to Herbie, which was cut down in 2010 while the 101-year-old tree warden watched. You are able to join the Liberty Tree Society and purchase clones of Herbie, as well as support their research into viable cultivars. This site also has a timeline of the fight to save the elms 

The study of DED tolerant elms continues. A cultivar developed in 1927, the Augustine Ascending elm, was once thought to have some resistance to the disease, although this has proven untrue. Of the 550 elms on the National Mall, a few of them are the Augustine Ascending cultivar. This variety may be noticeable due to its more upright nature. A specimen of Ulmus americana Augustine Ascending(B99) can be seen across the street from the tennis courts in City Park. 

The upright Augustine Ascending elm
The Augustine Ascending elm’s bark

Another cultivar with properties beneficial to fighting scale was discovered by Fort Collins’ own Tim Buchanan, then City Forester. Scale buster American Elm (Ulmus americana Scale Buster) is located near the trolley station. 

Although there is NO American elm listed on the current version of the Self-Guided Tree Tour, I have a sneaking suspicion this tree with its wooden American Elm sign is the same as the scale buster elm as a photo in the talk referenced above looks nearly exactly like the tree. This specimen is located behind the trolley station on the west side of the street. Before the leaves have bloomed it is quite easy to see its wooden sign if you are looking northeast.

The old marker designating the American Elm

*Sibley, David Allen. the Sibley Guide to Trees. 2015, Alfred Knopf.

Piñon Pine: Tastiest tree in the Southwest

Euell Gibbons may have proclaimed the piñon nut “the most palatable wild food.”

As you approach Santa Fe, you may notice hillsides covered with shrubby piñon trees. Nothing quite says you are in the Southwest as the crisp air carrying the scent of piñon pine. The smell of it burning wafts across the plaza in downtown Santa Fe. Plenty of stores carry piñon pine specialties, like piñon brittle, candies, nuts roasted with chile, and piñon coffee.

Leaves of the piñon tree

This species features in the traditions, legends, and ceremonies of many Southwestern cultures as described in a 1930s pamphlet from the National Parks Service. It may have been a major source of protein for Native Americans, including the Utes. For a modern discussion of the significance of the piñon to the Apache, this short blog includes a video and mentions piñon branches as smudge sticks. According to the site Pinenut.com, the nuts have had an economic benefit to the Navajo and in the 1930’s provided “more than the combined value of both rugs and silver which they produced.”

Piñon pine, Pinus edulis, is also known as Colorado piñon, Pinyon, common pinyon, New Mexico pinyon, Colorado pinyon, mesa pinyon, two-leaf pinyon, two-needle pine, nut pine, Rocky Mountain pinon, and Pino dulce. The preferred spelling, piñon, is Spanish and is interchangeable with most of the variations above. Although the USDA shows the trees throughout the Southwest, other sources indicate they are found primarily in Colorado, Utah, Arizona, and New Mexico. This discrepancy could be related to the existence of related species such as the single-leaf piñon, Pinus monophylla. Sibley* and others note the various species hybridize, making identification difficult.

Pinus edulis, the state tree of New Mexico, are “bushy” trees. They are slow growing but long-lived, possibly living up to 1000 years. The oldest verified tree was dated at 973 years, while the largest is located near Santa Fe, NM. As an alternate name suggests, this pine has two leaves in a fascicle, with the needles usually between 0.6 and 2.0 inches in length. The cones of the piñon are small, about an inch in diameter, and very round.* This species may not produce any cones until the trees are a quarter century old, with good seed production not starting until the specimen is 75 to 100 years old. As the fertilized seeds are comparatively heavy and not disbursed far by the wind, the species is dependent on birds to sow the seeds. Four species are primarily involved in this task: Clark’s nutcracker, Steller’s jay, Mexican jay, and the pinyon jay.

Although the seeds are what this species is known for, it is hard to beat its wood for a fire. The aroma is distinctive and quite pleasant. According to many sources, it provides nearly as many BTUs as hardwoods and has been called the “hardwood of soft woods.” Unfortunately, most sources lump piñon in with other pines, which might make sense on the national level. The benefits of burning in areas where it is available should not be overlooked. It is often cited as the best wood for chimineas.

Bark on the trunk of a pinyon pine

The sap, or pitch, of the piñon has been used by Native Americans in the Southwest for various tasks such as mending cracks in bowls, waterproofing baskets, and as an adhesive. The medical uses of piñon are, in general, lumped in with the properties of other pines. A tea of the needles is used to ward off scurvy** or for its expectorant effect***. The inner bark could be used to dress burns and other skin conditions. Piñon is said to have an antiseptic quality. These last two factors are why it is used to make natural salves today. Mother Earth News suggests the antiseptic qualities make it a good bathroom cleaner and air freshener.

Today the nuts themselves are the stars of the piñon tree. Multiple places proclaim their nutritional value, from saying they are as protein rich as beef, to suggesting they may be a good source of polyunsaturated and monosaturated oils.

My first encounter with piñon nuts involved the difficulty of shelling them. My friends who had gone to college in Santa Fe, insisted the best way to crack them was with your teeth. Although this method is okay if you are going to ingest them raw or roasted for yourself, the idea of cracking nuts with that method and cooking with them for others seemed objectionable to me!

According to an undated article in New Mexico Magazine, a secret shelling machine was invented by the founder of Buffett’s, an Albuquerque mainstay since 1956. The article also states you can purchase shelled piñon from them but I was not able to find any for sale on their site at this time, shelled or not. You ARE still able to buy piñon candy from them, including piñon brittle.

Numerous sites discuss the differences between “hard shell” nuts, those which are from Pinus edulis, and the soft shell nuts, Pinus monophylla, or Nevada nuts. The nuts of Pinus monophylla are larger, more resinous, and not considered as tasty. Euell Gibbons may have proclaimed the piñon nut “the most palatable wild food.” Many websites warn against buying Nevada nuts when you are after piñons. The New Mexico Piñon Nut Company ships nuts. Pinenut.com explained the 2021 supply is limited as the quarantine kept pickers out of the trees.

Not only the Native American population of the Southwest harvests piñon; many Hispanic families also gather the nuts in the fall. In many areas of New Mexico you see cars parked along the interstate and people scurrying amongst the trees. Harvesting your own nuts is the most economical. Although it is legal to gather nuts for your personal use in certain areas, it is best to know the laws. Some people shake the trees to remove the nuts or cones, but the traditional method is to pick off the ground as seen in this short video. Less traditional methods of picking and preparing nuts are discussed in this article where the author suggests breaking open the nuts with a rolling pin.

Fascicle and developing male cone (?)

Although most articles mention eating the pine nuts raw or roasted, recipes for their use abound. Fancy recipes such as pine nut soup, pine-encrusted pork, and a chocolate tart are including in this article from New Mexico Magazine. A number of recipes including candy and cookies can be found here. Native American Feast Day cookies feature piñons.

The piñon pine has also been used as a Christmas tree, living or cut. As is true for other features of the piñon, most lists of best trees for Christmas neglect to mention the species. New Mexico State University recommends them as having a good shape and says they are easily available for residents to cut. Every once in a while another publication will mention this conifer as a holiday possibility such as this bulletin from Washington state, which seems a bit out of their natural range!

A recent article discusses threats against piñon nuts and the trees themselves: climate change and cheap imports from other countries. Recent droughts have weakened the trees, which then are attacked by the ips, or bark, beetle. A study from California found higher temperatures decreased the viability of piñon pollen., while other studies have implicated heat death as the cause of the loss of between 40 and 80 percent of the trees. Not only are the trees and nuts endangered, but up to three quarters of the bird population may have disappeared in a decade.

Although it does little to solve the larger problem of the demise of the trees, it is still possible to use the logs as firewood if measures are made to destroy remaining beetles. In another glimmer of hope, the study mentioned above about the effect of heat, mentions a fungus that often grows with piñons may confer some drought protection.

By some reports nut harvests have decreased in yield by nearly seventy-five percent in less than fifty years. Indeed not all of the decline in piñon economy can be assigned to the change in climate. More than one article mentions the penchant for bulldozing trees in favor of ranchland or mineral and oil development as another factor leading to the decrease in productive piñons. The lower cost of imports doesn’t help the case for gathering the increasingly scare native product, either. In 2020-21 the cost of the nuts soared due to Covid-19 keeping pickers away.

In a 2014 publication, Rocky Mountain Forests at Risk, the authors discuss the importance of iconic trees in the Rockies and show possible scenarios related to drought, heat, and wildfire. They state the piñon-juniper woodlands are the most extensive type of forest land in the United States. They also mention piñons cultural significance as well as its role in water quality.

The Colorado pinyon (or piñon) pine in Fort Collin’s City Park

The Colorado pinyon (Pinus Edulis) can be found in City Park just northwest of Club Tico and across the road, near a power box. There are only two conifers in that area, and both appear to be piñon pines.

* David Allen Sibley, The Sibley Guide to Trees (Alfred A. Knopf, 2009, p.12)

**Linda Kershaw, Edible & Medicinal Plants of the Rockies (Lone Pine Publishing, 2000, p.36)

*** Michael Moore, Medicinal Plants of the Mountain West (Museum of New Mexico Press, 2003, p. 196)

The Difficulty of Defining a Fruit Tree, featuring Plums.

A tomato is actually a fruit but legally it is a vegetable!

Blossoms on the purpleleaf plum

What exactly is a fruit? My unabridged Random House dictionary has five definitions including: the edible part of a plant developed from a flower; part of plant growth useful to humans or animals; the developed ovary of a seed plant. (Random House Dictionary of the English Language, Unabridged, 1987.) More than likely the average person would say something along the lines of “the part of a plant that we eat” or name a few examples, such as a banana, raspberries, or apples. 

Saying a fruit is the part of plants that we eat does not distinguish a fruit from a vegetable, but then some botanists would say there is no such thing as a vegetable. Instead they might identify what we call vegetables as the specific non-fruit part of a plant which we eat, for example, the stem (rhubarb, celery) or leaf (kale, spinach) or root (beets, carrots). The botanical definition of a fruit is simply an organ which contains seeds, but complicating matters is the legal case defining a tomato as a vegetable. Nix vs Hedden was settled in 1893.Yes, a tomato is actually a fruit but legally it is a vegetable!

The purpleleaf plum leaves at their greenest later in the year

All flowering trees (angiosperms) produce fruit, not all of which we eat. According to Gollner, there are between 70,000 to 80,000 plant species which produce edible fruits. Of these, only about twenty species provide the majority of what we consume.* Other sources are even more pessimistic and say the human species relies mostly on TWELVE species of plant.

Excluding citrus trees, nearly all trees producing the common fruits we eat are members of Rosaceae, or the rose family. Genus Prunus includes plums, cherries, apricots, peaches, and almonds, all of which are drupes or stone fruits. Apples and crabapples fall into genus Malus. Their fruits are collectively known as pomes. Pears, in the genus Pyrus, are also pomes. Fruit cultivation probably began somewhere between 6000 to 3000 BCE, primarily in the Fertile Crescent and Eygpt. Some of the earliest domesticated fruits included figsdates, and olives

For eons, fruits eaten raw were suspect, with Pliny stating pears were not digestible and Galen suggesting fruits were “troublesome in everyway.”** Early crops looked little like what we now consume. This link provides a few pictures of early fruits

Prunus is the largest genus in family Rosaceae with the cherries and plums representing the most species. We do have native plums in North America, but information on all the species, often merely labeled “wild plums,” is difficult to come by. Some internet sources allude to many species, but the only place I found multiple species, about 30, enumerated was on a comprehensive map of wild plums throughout the United States. The accompanying blog post explains wild plums are becoming endangered due to the loss of animals (bears) to disperse the seeds. 

Is this the native plum tree?

The list of trees in City Park includes one native American plum (Prunus americana) tree. For nearly a year I have passed by where this tree is said to be located but have not been able to find a tag or determine any definitive characteristics (like evidence of fruit). It either isn’t there or is hidden in plain sight. Most sources list this species as being either a small tree, usually no taller than 25′ or a shrub with prickly twigs. The leaves, like others in this genre are serrated. The bark becomes scaly with age. The white flowers bloom prior to the leaves as early as March. Fruit is 1″ and turns reddish.***

Purple leaf plum was introduced to this county from Asia, is found mostly on the east and west coasts, although older literature shows a swath of the middle of the US as suitable habitat.

There are three purpleleaf plum trees in City Park, Prunus cerasifera Atropurpurea, also known as cherry plum, myrobalan or Pissardii. According to Dirr and Warren, the Atropurpurea variety is from the 1880s and may be the forerunner of many more recent cultivars. Although I have been observing these dark-leafed trees for a number of years, I have not noticed any fruit on them. This could be because, like the American plum, the fruit is only about an inch long. They do have beautiful pinkish white blossoms early in the spring. The foliage changes over the summer from deep purple to a dark green.

To find the purpleleaf plums (C123), walk along City Park Drive from the exit on Jackson Street until you find a cluster of trees in a space encircled with rocks. When they are in bloom, they are easily identifiable by the color of their leaves. 

If you want to try and find the American plum, walk along the ditch between Oak Street and Mountain Avenue and see if anything looks similar to a plum.

Dirr, Michael and Warren, Keith. The Tree Book: Superior Selections for Landscapes, Streetscapes, and Gardens, Timber Press, 2019.

*Gollner, Adam Leith. The Fruit Hunters: A story of Nature, Adventure, Commerce and Obsession, Schriber, 2008. p 23

**Ibid. p. 48

***Sibley, David Allen. The Sibley Guide to Trees.Knopf. 2015

The Cyme and the Bract: Other Lindens on the Tree Tour

Bracts are found on many plants and come in many different forms.

During bloom time lindens are easy to distinguish by their aroma and the clusters of small yellow flowers which resemble open tulips. After the flowers bloom and the seed, or nutlet, forms the linden can still be identified by the remains of the cyme, or flower clusters, and the bracts hanging along the branches. While still on the tree, bracts and cymes look like an extra, lighter green frill hanging below the leaves. 

The term bract was new to me, although on investigation, most of us are probably familiar with them in some form and think of them as “flower petals.” Instead they are specialized structures which protect the actual flowers of various species. Often, as in the case of poinsettias and dogwoods, we mistake the colored bracts for the flowers.  

Most of my resources say little about the cymes and bracts of the lindens. One website did talk about the bracts on lime trees, the British name for lindens. An interesting tidbit is that along with the flowers, bracts are harvested to make linden tea, which is known to help digestive disorders. It is also used as a sleep aid. The bracts alone may be made into a “beauty lotion” for cleansing the skin

Later in the year you have a clue you are under a linden when you find thin yellow leaves, which are actually bracts, under a tree. This year at least, these seemed to fall and scatter sooner than the actual leaves, but even when they are mixed with other leaves, they are distinctive in their thin, oval shape, rather like a tongue. 

There are a number of other linden trees on the City Park Arboretum tour. Most of them are either hybrids or cultivars. I can’t begin to tell a Greenspire Linden from a Redmond, although the first is a Tilia cordata and the latter is Tilia americana. According to Michael Dirr and Keith Warren in The Tree Book: Superior Selections for Landscapes, Streetscapes, and Gardens, each of these two trees, along with the many other cultivars, has its uses. The other cultivars found on the Arboretum tour are listed below with information from The Tree Book mentioned above. Numbers correspond to those on the Arboretum map.

C126 Tilia americana Sentry is narrower than most other versions and may have some resistance to Japanese beetles.

 C171 Tilia americana Redmond (C171) is said to be more urban tolerant that other lindens. 

Redmond Linden

C148 Tilia cordata Greenspire has the best pyramidal shape.

Greenspire Linden

C177 Tilia cordata Norlin is both a fast grower and cold hardy.

A83 Tilia x flavescens Glenleven is a hybrid between the American linden and the littleleaf linden and is known at the fastest growing linden hybrid. 

Glenleven Linden

E22 Tilia cordata Prestige. It seems little is written about this variety but it may be pollution resistant. 

C178 Tilia x flavescens Dropmore  The Dropmore linden is another hybrid which is viable to zone 2.

Dropmore Linden in bloom

C 149 Tilia cordata Fairview is said to have larger leaves.

Fairview Linden

 

 

 

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.

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.

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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Tilia tomentosa

 

Tea and Chocolate–Products of the Linden?

Honey from linden flowers is said to be some of the lightest and best available.

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Profusions of yellowish white linden flowers

By far the easiest way to find linden trees is during and immediately after they bloom as the clusters of flowers (cymes) give the whole tree a distinctive look, as if the undersides of the leaves have been painted a lighter color. The flowers also give off a fragrance that can be discerned from a distance. Most of the trees are quite tall and if they are tagged, it may be difficult to find the tag, but there is little mistaking a linden in bloom. Also helpful in identification when they aren’t blooming are the heart-shaped, but saw-tooth-edged leaves. The straight trunk and bark also help identify the genus.

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Grooved bark of the American linden

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Cymes of the linden with a single bract

Lindens bloom between May and July, although many sources mention June as the primary bloom time. The very fragrant blossoms come with a single bract and hang down like lacy umbrellas. Others have described them as “fireworks.”

In the US the American linden (Tilia americana) is also know as American basswood or just basswood. The range of this native tree in North America is the East and Midwest. In England, its European relative (Tilia cordata) is known as a Lime tree or little leaf linden.

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Tilia americana in bloom

Most sources state our native tree grows to a height of around 70′. The National Champion tree in a Kentucky cemetery, crowned in 2017, has a height of 102′. There is a tie for the largest American Linden in Colorado, with one tree in Fort Collins and the other in Denver. Both are listed at a height of 92′. Monumental Trees lists the tallest American Linden in Europe at 101 feet and the oldest specimen in the Netherlands as about 138 years old. Other sources have suggested the species can live for a thousand years!

Monumental Trees lists the tallest Tilia Cordata at 132.87 feet. This tree resides in the United Kingdom. One source states a tree in Britain is over 2000 years old, but Monumental Trees lists the oldest as a mere 820 years. In North America, the little leaf has been introduced in the most northeastern parts of the continent, where the normal height is said to be 50 to 60 feet. The US champion (height plus girth plus branch spread) is in the state of Maryland and only towers 83 feet. Colorado’s champion can be found in Denver at 89 feet, with the second place tree, 72′, found in Fort Collins.

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Tilia cordata

Native Americans made rope, netting, and baskets out of the inner bark, or bast, of the basswood tree. The wood is used for lightweight projects such as guitars and other instruments, carvings, yardsticks, and veneer. At one time basswood was the prime material for prosthetic limbs. The Iroquois carved the bark for ceremonial masks. The wood of the tree, being lightweight and fast-burning, may not be the best choice for heating.

According to the Kentucky Department of Horticulture, the American Linden was first cultivated in 1752. An oil derived from its seed pods was used as a replacement for olive oil, while the sap can be made into a drink or boiled into a syrup. Honey from linden flowers is said to be some of the lightest and best available. The preponderance of bees around the trees give rise to another of its nicknames, the bee tree, not to be confused with the Korean bee tree.

An usual product first made in the 19th century from the dried flowers and nutlets

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Nutlets on the little leaf linden

was a chocolate-like substance. Unfortunately this concoction did not keep well and production ceased. In a short article discussing this “chocolate” the author says it is still possible to make some for immediate consumption or to freeze and includes a recipe.

The flowers of the tree especially have many uses. In France the leaves were made into a tea (tilleul) and used as a mild sedative.

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Blooms on comes with a single bract

Cup of Linden tea
Cup of Linden tea. The tea bags are slimy but the taste is pleasant.

Since the middle ages, the tea has been used to cure headaches. Alternatively the flowers could be added to a hot bath to help insomnia. Even today the flowers may be used in the making of perfume, As an early variation of “forest bathing,” sitting under the trees was thought to be helpful to epileptics.

Usually made from the European species, Tilia Cordata, linden tea is a well known use of the trees’ flowers, leaves, and bark. Unlike many medicinal uses of plants, linden tea has had a number of scientific studies conducted and papers written. Many benefits, such as relieving hypertension, stomach issues, and pain, helping you sleep, and a reduction of inflammation are reported in alternative medicine articles. Along with benefits, most of these articles mention a few drawbacks, such as possible heart problems and drowsiness.

To find the trees in City Park, follow your nose! The American Linden (Tilia americanapictured in this blog is B98, which is across from the trolley station on S. Roosevelt Ave. There is another American Linden on the tree map at B101, which is located on north side of City Park Drive between fields 1 and 2. Tilia cordata, or the Little Leaf Linden (A 88), is also on the north side City Park Drive. It is the fourth stem in from the northwest corner of Roosevelt and City Park Drive, two down from the light post and near the little kids’ playground. These three trees almost form the points of an equilateral triangle.

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.

Lacebark elm trunk
Lacebark elm trunk

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.

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The lacebark pine

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.

Peeling bark on the lacebark pine

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.

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)

Bristlecone Pine–Cursed Tree or one That Changed History?

They are slow growers and may add as little as one 1/100 an inch of girth in a year

There are two species of bristlecone pine, both native to the southwestern United States. Pinus aristata, known as the Rocky Mountain bristlecone, hickory pine, or Colorado bristlecone, grows in the mountains of Colorado, New Mexico, and Arizona.

Bristlecone
Bristlecone in City Park

Pinus longaeva, native to Utah, Nevada, and California, is called either Great Basin bristlecone or Intermountain bristlecone. Both species are long-lived, but the Intermountain Bristlecone holds the record as possibly the oldest living specimen on earth. At first glance the name bristlecone seems to be due to the small branches with their short, stiff leaves which cause them to look a bit like bottle brushes. A third moniker for the Colorado Bristlecone is foxtail pine due to branches resembling those of foxes.

Close up of a branch
Small branches looking somewhat like a bottle brush

Originally both species were classified as foxtail pines (Pinus balfouriana) but were reclassified in the 1800s and the two types of bristlecone were further distinguished in the the 1960s. The actual reason longaeva and aristata are called bristlecone pines is due to a bristle on the young cone.

Both species belong to the five-needled or white pine group of Pinus. In Colorado, bristlecones typically grow from an altitude of 8300 to 13000 feet (Ackerfield.**) At higher altitudes they are slow growers. According to one source  they may add as little as 1/100th of girth in a year. Often bristlecones grow with both limber pines and Engelmann spruce and sometimes near treeline with common juniper. Their seeds are tiny. Unlike most other pine species, they are winged. The trees do not produce seeds until they are between ten and forty years old, but may continue to reproduce throughout their extremely long lives. Most references mention these evergreens retain their needles for many years, with one article stating the needles may persist for decades. Often the needles are sprinkled with white resin spots, making the tree look like it has suffered a case of dandruff.

Bristlecone closeup
Close up of a branchlet of a bristlecone pine

When discussing edibility or medicinal use of the bristlecone, sources such as Edible & Medicinal Plants of the Rockies (Kershaw, Linda, 2000) and Medicinal Plants of the Mountain West (Moore, Michael, 2003) tend to lump them in with other five-needled pines. Both sources mention pine needle teas to enjoy or use for coughs and fevers. Both sources warn an excess of the tea may be detrimental, especially to pregnant women. Pines may also provide resin and be used for firewood, although in national parks, all bristlecone pines are protected.

Dirr and Warren* mention the bristlecone for the landscape, especially in dry areas with poor soil. They do need full sun and are usually sold as cultivars. In the yard they may have the look of whimsical holiday trees. At higher altitudes they have the appearance of large pieces of misplaced driftwood.

Although Pinus aristata has evolved numerous survival mechanisms, and the ability to adapt to hardships may be part of the secret to its longevity, climate change may be playing a part in new dangers to these old trees. In the early 2000s, bristlecone pines were documented to have died from mountain pine beetle infestations. White pine blister rust and dwarf mistletoe are also known to endanger these long-lived trees.

A Pinus longaeva specimen known as Prometheus was counted as nearing 4900 years when it was cut down by graduate student Don Currey. There are various stories about how exactly this tree was destroyed with the exact facts in dispute.  A full reckonning of the acrimony and confusion surrounding the Great Basin bristlecone pine designated as WPN-114 has many facets of today’s fights about climate change. To make the death of this tree a greater tragedy, when the pith of the tree was sent to the University of Arizona’s Laboratory of Tree Ring Research after Don Currey’s death, a more precise dating of the tree was determined. Now some estimate Prometheus may have been 5100 years old. 

In a piece developed for Radiolab, the hosts play a recording of Don Currey telling part of the story of WPN-114’s demise. The piece on Prometheus begins around 15:00 minutes. Although interesting, there appears to be at least one mistake in the update. Prometheus lived in the Snake Mountains in what is now Great Basin National Park, while the White Mountains and the disputed new oldest tree is in California. 

In 2014 the artist Jeff Weiss produced an exhibit, or as he calls it “a thing,” to mark the 50th anniversary of the cutting down of this great tree. (There is a film about this “thing” discussing the history of the tree and the art; the story starts around 9:48. Although the information is overall interesting, there are a lot of extraneous comments.)

Another Pinus longaeva, Methuselah, is a mere fifty years younger and still living. And a third, even older tree is rumored to have been located by the same man (Edmund Shulman) who found Methuselah, but this has not been verified. The tree is said to be living in an undisclosed area of the White Mountains and was 5067 years old in 2019. The oldest Rocky Mountain bristlecone, which is located in Colorado, is a mere 2436 (in 2020) years of age. 

According to the Gymnosperm Database, the largest specimen of Pinus aristata is located in New Mexico. The tree may be of dwarf stature at high elevations but may reach 40′ at lower altitudes. The 2018 champion tree in Colorado was found in the San Isabel forest and reached a height of 59′, about twenty feet higher than the next candidate. Lower altitude trees may not reach the great ages of their counterparts closer to treelike. They may become victims of heart-rot, decreasing their longevity to around 300 years.

Bristlecone bark
Bark of the Rocky Mountain Bristlecone Pine

The Rocky Mountain bristlecone’s relative, the Great Basin bristlecone pine has also played a part in calibrating carbon dating techniques and helped correct the historical record. This was done by overlapping tree ring patterns from living tree core samples and intact patterns of deadwood. This technique has enabled dendrochronologists, archeologists, and historians to examine climatic and other patterns over 10,000 years and has earned the Intermountain bristlecone pine the moniker the Tree that Rewrote History.  Here is a link to a  2009  poetic documentary, The Oldest Tree on Earth: The Curse of the Methuselah Tree. It includes a clip of Don Currey discussing the cutting of Prometheus and information from the person who claims to have found an even older specimen.

The curse of the bristlecones implies those who touch/cut the trees will have brief lives. Edmund Shulman who cored Methuselah in the 1950s died at 49, while a 32-year-old Forest Service employ who helped carry a slab of Prometheus off the mountain suffered  a heart attack on the way down and died. Currey, who one would assume would be the most cursed, died at 70, diminishing the likelihood of a curse in my mind. A highly recommended 2020 New Yorker article by Alex Ross, “The Past and Future of the Earth’s Oldest Trees,” discusses the curse, dendrochronology, the controversy over the bristlecone’s possible submission to climate change, and other aspects of this species.

bristlecone against the sky
Colorado Bristlecone pine hiding amongst the spruces.

To find C170 Pinus aristata in City Park, go to the intersection of Mulberry Street and Sheldon Drive. On the northeast corner is a small grove of trees including some spruce and deciduous trees. The shortest of the conifers should be the Colorado Bristlecone pine. Last I  looked, I did not see its tag. This tree was planted in 1978 when it had a diameter of eight inches.

 

 

 

 

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

**Flora of Colorado (Ackerfield, Jennifer, 2015)

 

 

By the Beech

An unusual use of the buds in the spring is as a toothpick.

When interviewing Molly T. Roche, Senior Forestry Coordinator for the City of Fort Collins, back in 2018, I suggested we take her photo near one of her favorite trees. She selected the European Beech. We took the photo that summer, but I was hoping to include another when its leaves had turned. A cold spell and snow ensured the leaves on most trees crinkled up and turned brown. I waited through this fall but once again, didn’t get a photo.

Molly by the Beech
Molly by the beech, summer 2018.

Although there is an American Beech (Fagus grandifolia) which is native to the East and Utah, the tagged tree in City Park is a European Beech (Fagus sylvatica.) This species has been introduced to North America and similar to the native Fagus, grows in the east and Utah. Beeches belong to the Beech, or Fagaceae family, which includes the oaks, chestnuts, chinquapins, and two other genera that grow mostly in Asia.

The young leaves of the European beech are edible. Some say they haveSunlight through the beech leaves a taste somewhat like sorrel, which if you’ve never eaten it, has a lemony flavor. The leaves can be steeped in gin to create an alcoholic drink or made into a tea. And although this is NOT mentioned often, at least one company in the US makes a syrupBeech syrup from the American beech (Fagus grandifolia) sap. Granted this is not the same type of beech as in the park, but it is still interesting. A study done in Maine has cited a change in Northern forests from maples to beeches due to climate warming. Possibly a switch to Beech syrup can help save some of the current maple sugaring jobs.

Beech seeds, also known as beech nuts, according to most sources are quite tasty, although they may take a bit of work to prepare. Some may roast and grind seeds as a coffee substitute. Although a few seeds may be produced by the time the tree is 10 years old, trees do not fully produce nuts until they are 40 to 80 years old. An unusual use of dried beech buds is as toothpicks in the winter!

According to Monumental Trees, the beech tree trunk with the most girth, over 28′, can be found in Germany as can the tallest (>161 feet). According to the Sibley Guide to Trees (Sibley, 2009), a more usual height for a tree planted in North America is 50-70 feet. The internet site lists the oldest known Fagus sylvatica as a tree in Italy of 520 years. A “tree” planted around 1850 in Massachusetts is listed as the oldest known European beech in the US.

Sources vary on how useful the wood of a beech is for woodworkers. Most mention some furniture making as well as use in parts of instruments such as drums. Beeches in Europe have been used to construct cabins and furniture. Logs are used as firewood. They split easily and burn well. They may also be turned into charcoal or used to manufacture creosote.

The verdict seems to be out on using beech wood or chips for smoking foods. Most lists on the internet leave it off. One says it is long burning but has a strong flavor. Another says it is mild, similar to apple or pecan. This last mentions it is popular in Germany and used to smoke dishes such as Nuremburg bratwurst.

Beech trunk
The gnarly, elephant look of the beech trunk

There is controversy about the medicinal use of the beech, too. Although many sites mention some uses for its oil, leaves, and bark, most warn about toxicity or difficulty in procuring enough seeds or oil to be of much use. Other sources suggest even the bark may be ingested to improve digestion, and decoctions of seeds have been used to improve kidney function. Poultices made of the leaves have been used for headache relief and a tar made from the beech may be considered an antiseptic and has been applied for toothache relief.

A bestseller written in 2015, The Hidden Life of Trees: What they Feel, How they Communicate–Discoveries of a Secret World by Peter Wohlleben, which has received many good reviews, talks about the life of various trees but features beeches. The book isn’t without controversy, though, as seen in this article from The Guardian. The book almost reads like a novel but is backed up with scientific studies. It will certainly change how you look and think about trees.

To find Fagus sylvatica, go to the section of the park bordered by Oak Street,  Roosevelt and City Park Drive. The tree is somewhat in the center of the corner of Oak and Roosevelt. Currently it also sports a bright green box that might look something like a birdhouse but is actually a trap for some sort of bug. A second tagged beech in the park may be found along the lot line with the golf course.

 

According to The Tree Book ( Dirr and Warren, 2019,) the first cultivar of a European Beech was developed in 1770. Fagus sylvatica, Dawyck Purple is of the fastigate type and according to Dirr and Warren may grow to a height of 40-50′ (p.353.) This specimen has lovely, purplish-red leaves.

The Purple European Beech may be viewed along Jackson Ave, almost across from the intersection of West Olive Street.