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.
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.
E17Silver lindenspecimen 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.
Honey from linden flowers is said to be some of the lightest and best available.
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.
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.
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 Treeslists 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.
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
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.
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 americana) pictured 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.
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) E48head 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)
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.
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.
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 reasonlongaeva 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.
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.
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 Yorkerarticle 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.
To find C170 Pinus aristatain 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)
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.
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 have 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 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.
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.
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.
Fully leafed out beech
Beech in early spring
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.
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Fagus sylvatica Dawyck Purple
The Purple European Beech may be viewed along Jackson Ave, almost across from the intersection of West Olive Street.
Modoc cypress does not have a widespread natural range and is found naturally only in northern California and southern Oregon. At least one source calls this species the northernmost and hardiest of its genus, but its need for sunlight and susceptibility to fire seem to contradict the hardiness designation.
In 1898 this species was discovered in Modoc County, California by the botanist Milo Samuel Baker, an important collector and teacher during the early years of the last century. Not only is this tree known as Baker Cypress, Modoc Cypress, or Siskiyou Cypress but there appears to be controversy as to its scientific name. Proposed Latin names are Callitropsis bakeri,Hesperocyparis bakeri, Cupressus macnabiana, or Neocupressus bakeri. The second name is currently used in the USDA plants database. The nomenclature used on the tree tour map and often on the web, is a fifth destination, Cupresses bakeri, one of the older names given in the Gymnosperm Database.
Modoc Cypress is listed in Threatened Conifers of the World and on the Red List as Vulnerable. This may have to do with fire suppression practices as the cones do not normally open to spread seed unless subjected to heat, but the tree can be susceptible to fire damage. The thin, curling bark of the younger trees may also be detrimental in a forest fire. The reproduction cycle of this species is discussed on the above site. When the small, hard cones open, the seed is distributed by wind or rain.
Although there is some information about the medicinal use of cypress, it is also classified as a neurotoxin and is often associated with death. The same website mentions some species are planted in church yards and cemeteries. In the correct dosage some species of cypress may have medicinal and cosmetic properties, but no specific mention is made of the Modoc Cypress.
In City Park Modoc Cypress (D197) may be found near the frog sculptures, closer to Sheldon Drive. To me the cypresses can be identified by a hazy aura around them, probably an illusion from their interesting leaves.
The Latin name for this tree features a misspelling.
Once again, like many other species of oak, the chinkapin oak is native to most of the United States east of Colorado as well as in two states sharing a border with the Centennial state, New Mexico and Oklahoma. This species, Quercus muehlenbergii, is also known as chestnut oak, yellow oak, common chinquapin oak, rock oak, rock chestnut oak, and yellow chestnut oak. It is one of those oaks whose leaves the uninitiated might not consider to be oak leaves. Instead, with their ragged or sawtooth-like edges, they could be mistaken for elm or chestnut leaves .
The acorns of this species of white oak are considered of the best eating quality. They are an important food for a variety of birds including woodpeckers and turkeys, as well as black bears and many small mammals and deer. The Chinkapin oak could be considered instrumental in the mobility of this country as the logs were once used as fuel in steamships. Later, logs were used as railroad ties. The wood is often fashioned into cabinets and furniture. The tree also has a few medicinal uses as an antiemetic and astringent.
In the wild the trees grow to 60-80′. Cultivated, they may only reach about fifty feet. The current champion tree in the U.S. grows in Virginia. It stands 66′ tall with a crown spread of 113′. The four trees listed as Colorado champions, all of which are in Denver, range from 62 to 66 feet in height but the largest tree has an overall point value (height plus crown spread plus trunk circumference) of less than half that of the national champion.The oldest recorded tree in the US is around 343 years old and can be found in Springfield, Ohio.
Where did this species get its common name? It bears a similarity to a tree in the same family (Beech) but a different genus and species, Castanea pumila, which has an overlapping range with the oak species. The Allegheny chinkapin, also called a drawf chestnut, is a small tree or shrub with a single burr containing a nut. The leaves of this species look very similar to those of the Chinkapin oak, but the lack of an acorn should be a distinguishing feature.
The Latin name of the chinkapin oak has a convoluted history, complete with a misspelling. In the past this species was considered to contain three varieties of trees, but on reclassifying and renaming, the species was given the Latin name Quercus muehlenbergii by George Engelmann, which would account for the full name Quercus muehlenbergii Engelm.
And the misspelling? When Engelmann honored Muhlenberg, he used the German spelling with an umlaut, which when transcribed resulted in the muehlenbergii spelling. Both spellings are now sometimes used.
There are two chinkapin oaks identified on the Fort Collins City Park Tree Tour. One is located in the quadrant bordered by Jackson and W. Mulberry. This specimen (C159) is in a group of trees and may have lost its identifying tag. The second tree (E16), located behind the fire station in the southwest corner of the park, was planted in 1996. It also appears to have lost its tag. The tree can be found on the peninsula between the parking lot and the roadway, near a fake rock.
In Texas the acorns may be the size of golf balls!
While the spelling of bur oak is sometimes burr oak, according to Sibley* it is also called a mossy-cup oak or blue oak. The Lady Bird Johnson Wildlife Center adds more names to this list, including Savanna oak, overcup oak, prairie oak, mossy-overcup oak. To add to the confusion, in certain terrains it can be referred to as scrub oak. It would appear some of its names are related to the various habitats in which this species, Quercus macrocarpa, grows. Alternatively, it refers to the appearance of its acorns.
This white oak is native to much of the eastern and midwestern United States and Canada, although its characteristics vary depending on its location. According to Iowa State University, this tree has the most variable characteristics of any of the oaks. For example, its acorns are large in its southernmost growth area while they can be about a fifth the size in the northern regions.
The overall height of the tree also varies by its habitat. In northern climates it may only grow to half the size of the same species in southern latitudes. This year saw a new national champion bur oak be honored in West Virginia. This specimen is a bit over 107 feet tall and has a trunk circumference of more than 278 inches. Models of climate change have predicted bur oak may have an increase in its range, but the locations where it thrives may also shift. Due to its long taproot it may be able to withstand drought conditions.
Its acorns can be the largest of the native oak species and are well fringed, hence its mossy-cup moniker. Its Latin name is related to the acorns; marco means large in Greek and carpa refers to fruit. One author states burr oak acorns in Texas are golf-ball sized! Iowas State University allows the trees do not bear fruit until they are 35 years old. Most sources state the trees can live 300 to 400 years. The university site also states the lumber of the tree can be used like white oak, but isn’t as valuable due to its many branches. The USDA mentions the most valuable bur oak trees for lumber come from Iowa and Illinois where it is usually marketed generically as white oak.
The trees provide food to 96 or more species of wildlife, including black bears. According to this article, acorns are the primary high quality food source for black bears in northeastern Minnesota. Cattle and other livestock may ingest seedlings and acorns even though this material may prove poisonous in large quantities. This same source specifically mentions the Cheyenne of Montana as having eaten a mixture of acorns and buffalo fat.
Like other trees in general, and other oaks in particular, parts of the bur oak have been used medicinally. A unique mention is made of tree galls used to treat intestinal problems and as an antiseptic.
The tagged Quercus macrocarpain Fort Collins City Park was planted in 1979. It is located between the reservable shelter and the road to the golf course. Look for the electrical box painted with a black cat. If you point to the east at a diagonal from the box, you should be in line with the tree.
Sibley, David Allen. The Sibley Guide to Trees, 2009.