The Ancient Cross Timbers Forest

The Ancient Cross Timbers Forest

Article by Diane Wetherbee, Citizen Forester Liaison

Cross Timbers Road. Cross Timbers Development District. Cross Timbers Gazette. It seems everywhere you turn in North Texas, you see the words “Cross Timbers.” Newcomers to the area may wonder what the Cross Timbers is and why it’s so important that it is immortalized in names all over the area.

The Cross Timbers Forest is the last of the forests early European settlers encountered as they traveled from the east to the west. Look at any two maps, and none will agree on the exact location of the Cross Timbers. The forest isn’t a single continuous band of trees, but instead is a mosaic of forests with prairie glades throughout. It runs generally north and south, stretching from southeast Kansas, through central and eastern Oklahoma, then through north central Texas all the way to the Waco area. Post oaks and blackjack oaks are the predominant species, along with hickory, elm, and hackberry trees. The understory is a tangled mess of vines, briars, and dense shrubs, nothing like the neat pine forests of East Texas.

Plant ecologist Suzanne Tuttle, retired manager of Fort Worth Nature Center, explains that the Cross Timbers Forest is two separate bands of that ancient forest mosaic, each growing on distinctively different soil types. The Eastern Cross Timbers, which runs through much of western Denton County, including Flower Mound and Lantana, is a narrow band no more than 15 miles wide, with coarse, sandy soils over sandstone. The Western Cross Timbers, a much wider band located generally just west of Fort Worth and stretching almost to Abilene, has shallower sandy soils with a limestone base.

The Grand Prairie separates the two major forest sections, although there are many large stretches of prairie that run throughout the Cross Timbers. Long Prairie, which gives FM 2499 its street name, is one example of a very large prairie within the Eastern Cross Timbers. The Flower Mound, the 12.5-acre prairie remnant that gives the town its name, is the sole remaining tiny piece of Long Prairie.

If you’ve ever hiked off trail in the forests of North Texas, you’re well acquainted with the challenges the Cross Timbers must have presented to travelers during our country’s westward expansion: low-growing forests full of trees with gnarled limbs. blankets of thorny vines, and thick underbrush. Famous writer Washington Irving, author of The Legend of Sleepy Hollow and Rip Van Winkle, joined an expedition in 1832 to the Indian Territory (present-day Oklahoma). After weeks of hacking their way through the Cross Timbers Forest, Irving wrote, “I shall not easily forget the mortal toil, and the vexations of flesh and spirit, that we underwent occasionally, in our wanderings through the Cross Timber. It was like struggling through forests of cast iron.” And that’s how the Cross Timbers got its nickname, the Cast Iron Forest.

You must be tough to make your way through the Cross Timbers. The forest effectively cut off westward travel between the prairies to the east and the Great Plains of the wild western frontier. For those European settlers who were hardy enough to settle here, it helped protect them from raids of the Plains tribes living to the west, like the Comanches. That’s one reason you don’t hear many stories about Indian settlements or raids in Denton County. Native American tribes in this area were often nomadic, and they had to be tough to make their way through the Cross Timbers, as well.

Tuttle, the plant ecologist, warns that the relatively small size of the Eastern Cross Timbers makes it highly endangered, since so much of it is already developed. “The Eastern Cross Timbers is probably the most endangered ecosystem in Texas. It is small in acreage and is in the crosshairs of one of the most rapidly developing areas of the United States,” Tuttle said. Post oaks grow very slowly, and they often don’t look as old as they are. In untouched areas, the Cross Timbers has post oaks that are 200-400 years old, predating the birth of the U.S. Yet a 200-year-old post oak may only be 30 feet in height and not very large in circumference, and because of that, we often don’t recognize their significance.

These tough forest guardians have withstood our region’s ice storms, hail, strong winds, frequent droughts, and temperatures that range from lows near zero in winter to over 100 in summer. But by far their fiercest adversary is human expansion into the desirable North Texas area. They are sensitive to root disturbance, so building too close to the tree or running construction equipment over the root zone can cause a tree to die. Post oaks are rarely found in the nursery trade because they take so long to grow and are difficult to transplant successfully. Your best bet is to start with an acorn planted where you ultimately want the oak.

If you’d like to read more about the Cross Timbers Forest and its important role in forming our history and our current landscape, pick up a copy of Richard V. Francaviglia’s book, The Cast Iron Forest: A Natural and Cultural History of the North American Cross Timbers. It’s a fascinating story of the important part this strange, tough forest and prairie mosaic played in the settlement of North Texas, its continuing struggles for survival, and its sometimes dreary outlook for survival in the future. As Francaviglia puts it, “…despite incredible changes, the cast iron forest stubbornly refuses to disappear. Despite the passage of several centuries, the Cross Timbers still resonate with history and generate a sense of wonder.”

Appeared in The Cross Timbers Gazette, October 20, 2022

 

 

The Lost Maples of Vanderpool in the Texas Hill Country

The Lost Maples of Vanderpool in the Texas Hill Country

By Amira Hamdan

The four seasons in Texas are an elusive thing. Sure, you’ll find summer, and even for a month or two, you’ll enjoy the mildest of winters south of the Panhandle. (You’ll find real winter in the Panhandle itself.) Spring lasts about as long as a weekend flash flood. As for fall? Well, autumn is the hardest season to find in the Lone Star State. But if you head northwest, a little less than two hours from San Antonio, you’ll find it in Vanderpool. The Lost Maples State Natural Area puts on quite a show of red, yellow and orange in autumn.

In the last ice age, the range of maples was much greater and reached well into Texas. The Vanderpool maples are rare relics of that era, able to survive due to the area’s microclimate and uncommon soils. These trees are an ancient and colorful reminder of what trees do for local ecosystems  and how much of an impact they make.

What You’ll See

https://www.flickr.com/photos/atbaker/5177577110

New Englanders might take fall colors for granted — but not Texans. As much as Texans love their hot summers and mild winters, they go crazy for things Northerners take for granted, such as snow and red and gold autumn leaves. That’s because in most parts of the state, maples are not native plants and have a harder time surviving outside of this micro-ecosystem in Vanderpool. Native plants are vegetation that grows naturally and doesn’t need a lot of TLC to survive – like the live oak trees that dot the Texas landscape, or the yaupon, or the prickly pear cactus.

Of course, fall color depends on the weather conditions, and so the state puts out fall foliage reports online and on social media. You can get an idea of how intense the colors are before you hit the road. Vanderpool is also a scenic drive from the popular tourist towns of Fredericksburg and Kerrville. You can make Vanderpool part of a day or weekend in the Texas Hill Country. It’s a great excuse to get outside and enjoy Texas’ brief fall season.

How to Get There

San Antonio is the closest major city to this natural wonder. The fastest way to Vanderpool from SA is west on US-90 to Sabinal, where you hang a right on North Center Street. That turns into TX-127 for a while, and then it turns into Ranch Road 187 before depositing you at the Lost Maples. You’ll find the town of Vanderpool just north of the Lost Maples. If you’re coming from I-10 north of San Antonio, turn west on TX-27. Turn right on Ranch Road 187, which takes you right to the park.

Know Before You Go

https://pxhere.com/en/photo/1592045

Turns out autumn is so popular in the state of Texas, the Texas Department of Parks and Wildlife often has to close the park when it hits capacity. But you can reserve your spot at the Lost Maples State Natural Area. Once the sun goes down, the stars at night are big and bright at Lost Maples (which literally is deep in the heart of Texas) — and a treat for stargazers. There’s an entrance fee to Lost Maples State Natural. It’s $6 for adults, and free to kids 12 and younger.

Few people need an excuse to get away to the Texas Hill Country, but in November, you can add one more reason to run for the hills. The Lost Maples of Vanderpool will make you think — just for a moment — that you’re in an autumn wonderland, in one of the best regional vacation areas in Texas.

Amira Hamdan is a traveler who loves to write, and a writer who loves to travel. Plunk her down in a new place and she will find the best local cuisine by noon and the best campsite or B&B by nightfall.

You Can Call Me Sugar(berry)

You Can Call Me Sugar(berry)

Unique Trees of North Texas:

Sugarberry aka Hackberry

(Celtis laevigata)

By Laura M. Miller, Texas A&M AgriLife Extension, Tarrant County

In nice straight rows along just about every fence line, past or present, in North Central Texas, one is likely to find a few, often quite a few, of one of our most abundant native tree species, Celtis laevigata. Our native oaks are almost universally beloved, but this is a tree that does not get a lot of respect despite being one of the top three species in their contributions to tree canopy all over the Cross Timbers.

Warty trunk of the sugarberry

The name Celtis comes from Latin and is one of those examples of a misnomer that stuck. The name was originally used to refer to a completely unrelated berry bearing tree, Zizphus lotus. The genus includes 60-70 species that grow in most of the warm temperate regions of the world, including five of the seven continents. In addition to Celtis laevigata and its subordinate taxa (more on that later), Texas is also home to the very widely distributed Celtis occidentalis which is known as Northern or common hackberry. C. laevigata can be distinguished from C. occidentalis by its narrower, smoother leaves. Laevigata means smooth which is kind of ironic because its bark is anything but smooth. Many descriptions call it warty, and it is a favorite of tree vandals who appreciate the abundant scar tissue it forms providing a pretty noticeable record of exactly who “was here”.

The taxonomy of this tree can be confusing. Celtis used to be a part of the elm family but is now in the hemp family. At times Celtis reticulata, Netleaf hackberry, was considered a separate species, but now it is a variation of Celtis laevigata, C. laevigata var. reticulata. Mature trees in preferable sites can reach 50 feet in height but most specimens will be much smaller. It is not considered to be a long-lived tree as wood decay can be an issue, but it is possible for trees to survive for up to 150 years. As with any other landscape tree, pruning a young tree to a central leader will greatly improve the odds that it will have a long and happy life as well as result in a more attractive tree.

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Sugarberry seedlings with three true leaves (left) and cotyledon leaves (right)

In addition to fence rows, Sugarberry can often be found growing along the streams and rivers of the Cross Timbers. It can tolerate a wide range of annual rainfall, anything from 20-80 inches per year and grows in a wide variety of soils. Those aptly named sugary berries are consumed and subsequently spread by a wide variety of birds and mammals. Its value as a food source to wildlife is where this species shines. The “sugar berries”, small round drupes, are set early in spring and often remain after the leaves have fallen. Both resident and migratory birds enjoy them. Anyone who wants to attract mockingbirds, bluebirds, cardinals, doves, robins, cedar waxwings, orioles, and warblers, along with plenty of sparrows, should consider planting a sugarberry. You can also simply not cut down ones that will certainly appear under any place birds sit. The berries are highly successful at germinating in any space that a mower can’t quite reach.

If butterflies are your goal, this tree is a larval food source for emperor, snout, question mark and hackberry butterflies. In the summer of 2015, people who had never given their sugarberry trees a second look suddenly noticed the presence of webs and absence of leaves, especially in northeast Tarrant County.

Hackberry nipple galls on sugarberry leaves

The causal insect was eventually identified as Sciota celtidella, which in most years blends into the background about as well as the average sugarberry.

While birders and butterfly enthusiasts might want a sugarberry or two, anyone who enjoys gall making insects could not plant a more interesting species. It is a challenge to find an individual tree that does not have any galls. The most common is in fact used to identify the species. Known as the Hackberry nipple gall it is formed by a psyllid.

Although commonly occurring and often overlooked, sugarberry is uniquely valuable as a source of food and shelter to the birds, bees, butterflies, and other inhabitants of the Cross Timbers.

Blackjack Oak Tree

Blackjack Oak Tree

Unique Trees of North Texas:

Blackjack Oak

(Quercus marilandica)

By Jeremy Priest

This interesting oak species is often an associate of the better-known post oak, but blackjack oak is even more drought tolerant and survives on some of the toughest sites around. Owing to these extremely poor sites, blackjack oak often seems to be a smaller, stunted oak, with 100-year-old trees sometimes only being 20 feet tall and only a foot in trunk diameter. Don’t let it fool you though, blackjack can make for a beautiful shade tree and grows quite large when water is adequate. It is never a fast-growing tree, but on good sites growth rates may be nearly double that of post oak. The limiting factor for blackjack oak is an extreme intolerance to shade. This tree needs full sun so much so that its lower branches are easily shaded out by the upper canopy of the tree. Much like bald cypress evolving to tolerate extremely wet sites, blackjack oak has evolved to tolerate very poor and dry sites so that it can achieve full sun.

The common name most likely relates to the leaf shape and dark appearance of these trees. Not only is the bark dark and almost black, but the large thick leaves provide heavy shade. This tree also uniquely retains its dead understory branches and during the winter has leaf marcescence. This can lead to an overall spooky appearance when multiple blackjack oaks grow near each other. Most of the time the dead branches add to the look of the tree and there is no reason to remove them, unless there is a strong likelihood of damage if the branch were to fall. Since these lower branches are dying due to shade, these dead branches do not represent an issue with the tree, and it is completely natural for blackjack. If branches on the top of the tree die then there is a problem with the tree.

 

Blackjack oak is fairly easy to identify from overall appearance, but the leaves are also quite distinct. As with other oaks they are simple, with a smooth margin, and are arranged alternately. For blackjack the leaves are large and only have three somewhat rounded lobes which are not deeply cut into the leaf, although this varies considerably. The leaves are very dark and thick, with points at the tip of the lobes as blackjack is considered a “red oak”. Most oaks with rounded lobes fall into the white oak category, so look for the bristles on the tips of the leaf to ID blackjack oak. The bark is very dark, but does have a red appearance underneath if damaged. Like all oaks, this tree has acorns which are small but otherwise fairly normal.

Although the scientific name of this species means “of Maryland”, this tree is native across most of the southeastern US and encompasses the Cross Timbers region. Blackjack oak is not tolerant of highly alkaline soils which is why it has a slightly narrower range than post oak. The minimum annual rainfall needed is 17 inches according to USDA Plants Database, and it does not tolerate anaerobic conditions, i.e. flooding. One of the densest populations of blackjack oak in Arlington’s parks is at the Southwest Nature Preserve. This upland site is very dry and rocky but is also acidic and iron rich which is visible in the exposed red soil on the hilltop.

The native range of blackjack oak includes the Cross Timbers

As mentioned before, this a red oak species which most notably means there are no tyloses in the xylem vessels. Blackjack is shade intolerant as with most red oaks and though decay resistance is still high, there is less decay resistance than the white oak family. However, blackjack is extremely drought tolerant and can survive with minimal annual growth which is not normal for red oak species. It also has an extremely long lifespan, probably exceeding 100 years. The average lifespan is not easy to predict as this tree is not very common, but there is probably high mortality when young. Blackjack oak does not like competition and needs full sun, but otherwise experiences few health problems. If planted, soil drainage and pH could be an issue for tree health. Blackjack oak can reach heights of 40-50 feet and crown diameters of 40-60 feet. The largest one I’ve seen in Tarrant County (top photo) was over 30 inches trunk diameter and would have been one of the largest on record in Tarrant County. This large tree was probably over 110 years old, unfortunately it was recently removed, perhaps because the developer did not understand the value of a large blackjack oak. The state champion tree is in Henderson County and is 43 inches in diameter with a height of 65 feet.

Hercules’ Club Tree

Hercules’ Club Tree

Unique Trees of North Texas:

Hercules’ Club

(Zanthoxylum clava-herculis)

By Jeremy Priest

This aptly name tree certainly deserves a spot on the “unique” list. Hercules’ club, which is also known as toothache tree, tickle tongue, pepperbark, or prickly ash, is part of the Zanthoxylum genus. The genus has many species with overlapping or similar common names, but only 3 other Zanthoxylum species grow in Texas (Texas Hercules’ club, lime pricklyash, and tickletongue). Many of the common names associated with this species refer to the stimulating nature of the bark and wood of the tree. The tree was historically used by Native Americans and early settlers to numb the mouth, hence the name toothache tree. The name Hercules’ club is easily noticed in the scientific name and fits the appearance of large specimens. When young, the tree develops sharp spines on the bark (not just at leaf nodes as with some other species) which are usually distributed throughout the trunk and branches. As the tree ages, the prickles develop corky, pyramidal bases and eventually lose their sharpness. These corky structures may eventually develop strong ridges as seen below. No matter the age, the trunk of this tree always looks like it could be fashioned into a fearsome weapon.

To identify Hercules’ club look for the distinct spines on the trunk and branches and pinnately compound leaves. Typically 5-19 leaflets, including a terminal leaflet, that are 0.5-4.5 inches long. Small greenish white flowers form in the spring at the tip of branches and seeds are shiny black but not very conspicuous. Don’t confuse Hercules’ club with devil’s walkingstick (Aralia spinosa), which grows straight up with very little branching and has doubly compound leaves. While the leaves may be similar to other compound leaved understory species such as sumac, or the spines similar to species such as honey locust, Hercules’ club is quite distinct and easily distinguished from all except other members of Zanthoxylum. Texas Hercules’ club is more common farther south and west and is a smaller stature tree with only 3-7 leaflets (5 is typical) 0.5-1.5 inch long with the entire leaf less than 4 inches long. Texas Hercules’ club also does not develop the strong corky bases on older prickles. The national champion Texas Hercules’ Club is in North Richland Hills with a height of 22 feet and a spread of 20 feet.

Hercules’ club is an understory tree that typically grows to less than 20 feet in height; however, it is only moderately shade tolerant and relies on establishing with limited competition. The seeds are popular with birds and remain viable after being eaten allowing the species to spread profusely along fencerows and transition zones. Another way it establishes with limited competition for light is to grow on poor sites such as upland, dry, or very sandy areas. In the Cross Timbers region, the overstory on these sites often consists of post oak and blackjack oak. As the tree is adapted to grow on harsh sites with low overall plant density, developing spines reduce wildlife browsing and helps Hercules’ club outcompete other vegetation. If the tree is to be planted, select a relatively dry area with good sunlight. Also remember that the spines on the trunk can be a concern but can be removed or the tips cut if needed. The sharp spines usually do not grow back as the bark develops.

Hercules’ club is native throughout the southeastern US extending from Florida to central Texas. It is tolerant of acidic and alkaline soils. This species also prefers well-drained or sandy soils and does not tolerate flooding. Some of the largest Hercules’ club in Arlington are found at the Southwest Nature Preserve, which is known for being a dry, upland site with some unusual species. There may also be Texas Hercules’ club at the nature preserve as some of the trees develop drastically different bark texture and smaller leaves. Another Arlington park where Hercules’ club is prevalent is Cliff Nelson, which has similar site conditions to the Southwest Nature Preserve. Fully grown the tree may reach 20 feet in height and 15-20 feet in crown diameter, with a trunk diameter of 8-12 inches in 30-40 years. Given the poor sites on which these trees are found they do grow somewhat quickly, as much as 1 foot per year in height. The largest Hercules’ club reported in Texas is in Nacogdoches County (East Texas) and has a height of 38 feet and a trunk diameter of nearly 20 inches, although trees in the Cross Timbers would not likely grow this large.

 

Sources

Vines, R. A. (1982). Trees of north Texas (Vol. 14). University of Texas Press.

Mexican Plum Tree

Mexican Plum Tree

Unique Trees of North Texas:

Mexican Plum

(Prunus mexicana)

By Wes Culwell

The native range of Mexican plum consists of a large portion of the midwestern United States.

Every March, Mexican Plum trees proudly display their dainty white blossoms while they compete in early spring with maybe the more popular Redbud trees, as the Redbuds catch our eyes with their pinkish-purple blooms.  But with close inspection, we find that the Mexican Plum is really a beautiful senorita with her delicate and beautiful blossoms and a unique and wonderful bark.  Since neither of these trees grow as a monoculture, they can sometimes be found blooming in small groups together.  They are our first native trees to remind us that once again spring is here.

So, let’s look at this Texas native’s two most popular features: the flowers and fruit.  The flowers are fragrantly strong and sweet with white petals and about 1” in diameter and usually in more of a mass than redbud flowers. And of course, they bloom before any leaves are present.  The fruit then begins to grow in midsummer and matures in September.  The mature, purplish-red round plums are up to 1” and are edible and can be eaten fresh or used in jams and jellies.  However, one must beat the birds and mammals to the plums.

A mature Mexican plum with distinct spiraling bark.

Although Mexican plum is known for its flowers, the bark is definitely unique and beautiful.  The bark is tight and smooth and a metallic gray when it’s very young.  As the bark matures, it becomes a wonderful brown that is exfoliating, papery and scaly.  Very mature trees have deeply furrowed and rough bark that often develops a spiraling grain.

The Mexican Plum will grow in sun or moderate shade.  This small tree may reach 20 feet tall and wide and is deciduous with alternate, simple leaves on sort of irregular branching of the twigs and limbs.  I can’t say with conviction that the leaves are attractive, but they are unusual.  The leaves have a felt-like feel on the upper side and during the growing season they appear coarse-looking and usually about 2-4” long.  Most of the time, the leaves are folded over at the edges and appear water deficient even though it is a drought tolerant tree.  But the leaves make a big come back in the fall with beautiful yellow and orange colors.

The leaves and late summer fruit of Mexican plum.

This tree is easy to grow in most locations and once established, it requires little water or fertilizer.  It can be a little difficult to transplant from the wild, but can be easily grown from seeds planted in the fall or after cold stratification.  From experience, you must protect them during the germination time period from squirrels who may like them more than acorns.  Propagation can also be done by stem or root cuttings.

 

This little Mexican maiden needs to be used much more as an ornamental tree in our landscapes.  It can be used as a great alternative to dogwood trees, especially in clay or alkaline soils and dry sites that are detrimental to other species such as dogwood.  The next time you think “This is a great place for a redbud,” try to remember this beautiful delicate bloomer.  If you have to plant a redbud, plant a Mexican Plum to go with it, you won’t regret it!

Texas Ash Tree

Texas Ash Tree

Unique Trees of North Texas:

Texas Ash

(Fraxinus albicans Buckey, formerly Fraxinus texensis)

 

By Craig Fox

Texas ash leaf identification

Pinnately compound leaf of Texas ash with 5-7 rounded leaflets

Ash trees, particularly in Texas, are a hot topic of conversation in the arboriculture world. After the formal confirmation of Emerald Ash Borer (EAB) in Tarrant County, ash trees seem to be on everyone’s mind and rightfully so. Though not nearly abundant here as in the Midwest where EAB originated domestically, North Texas has a modest population (about 2-4% of the urban forest) of ash trees at risk to the destructive pest.

Perhaps the most common ash in the western Metroplex is Texas ash. Just as other members of the genus Fraxinus, they have opposite bud and branch arrangement and pinnately compound leaves. Texas ash typically feature five to seven leaflets (fewer than what is common for green or white ash) rounded in shape with possibly a slight point at the tip. They display excellent fall color in hues of purple, reds and oranges–usually in November–before shedding all their foliage. Texas ash have narrow samaras, or winged seeds, with wings that generally do not extend past the mid-point of the seed and which may persist through winter.

Texas ash regional champion tree in Fort Worth

DFW Regional Champion Texas Ash, located inside Fort Worth’s historic Pioneers Rest Cemetery which was created in 1849

Though they may grow to forty feet tall or larger, most Texas ash in our area tend to be smaller, probably due to the thin, rocky soils they natively inhabit and their relatively short lifespan. Large concentrations can be found on fossiliferous limestone ridges through areas such as the Fort Worth Nature Center & Refuge, around Lake Worth and through areas near Aledo, Azle and Weatherford, though it does often appear elsewhere in the DFW region. They are often found intermingled with Texas red oak, eastern redcedar, post oak and cedar elm in our area. Texas ash may be single trunk or multi-trunk and frequently found in colonies. Ultimately, their native range spans from a few counties in Southern Oklahoma near the Arbuckle Mountains, along a thin band into North Central Texas, eventually skirting the Balcones Escarpment and crossing into Northern Mexico.

During leafless periods, ash species are notoriously difficult to differentiate. Texas ash have “C-shaped” leaf scars where the bud sits within the cup of the “C”, very much like the white ash to which they are closely related. In fact, some botanists believe that Texas ash is a subspecies of white ash (Fraxinus americana). The botanical name was changed to Fraxinus albicans Buckley from Fraxinus texensis to correct a complicated issue of proper nomenclature (I still tend to use texensis for obvious reasons).

 

identifying Texas ash

Clockwise from top left: Year old samaras of Texas ash; older bark (l) contrasted with younger bark (r)-diamond pattern not well formed on either tree; “C-shaped” leaf scar-note how the bud sits within the cup of the “C”

The DFW Regional Champion can be found in Fort Worth’s historic Pioneers Rest Cemetery—a worthwhile visit for the history, if not the tree. Located just north of downtown at 620 Samuels Avenue, the tree is the lone example of its species within the grounds and is officially recognized by the City of Fort Worth as a heritage tree. The state champion tree is located within Lost Maples State Natural area in Bandera County. Curiously, American Forests claims that the National Champion Texas ash is perched just south of Lake Ontario near Rochester, New York—well outside its native range and far removed from what seems to be the preferred site conditions.

Fraxinus is the Latin word for “spear”, while the common name ash is derived from “aesc”, an Anglo-Saxon word. Norse mythology states that humans emerged from Yggdrasil, a great ash tree spanning the cosmos and that both Odin and Thor owned spears made from ash. Vikings were sometimes referred to as “aescling”, translating to “men of ash” for the spears their warriors carried. Planks for ships, oars and chariot axles were commonly made from ash timber. Today, the wood of ash trees is popular for use in tool handles and baseball bats due to its shock resistance. It is also popularly used to create flooring and millwork.

All Fraxinus species in Texas are believed to be susceptible to attack by EAB, but some research indicates that green ash (Fraxinus pennsylvanica) is the preferred host. The beetle, Agrilus planipennis, is native to East Asia where it is rarely problematic within its native range. Believed to be introduced into North America in the late 20th century, the borer was formally discovered in Michigan in 2002. The confirmed location in Tarrant County occurred in 2018 along Ten Mile Bridge Road, just north of the Fort Worth Nature Center & Refuge. Due to the extensive activity and damage found at the site, it is believed that EAB was present, but undetected, in Tarrant County for several years prior to discovery.

Evidence of EAB occurs in the upper canopy first, which can be hard to detect, but an increase in woodpecker activity could help provide clues as the birds actively feed on the larvae. A thinning upper canopy and epicormic shoots near the base of limbs or along the trunk are also common symptoms.  After hatching from eggs laid in bark cracks and crevices, S-shaped galleries which gradually open in shape are created beneath the bark as the EAB larvae chews through the tree’s phloem. Due to the extensive feeding and destruction of cambium and phloem, the bark will eventually begin to peel, split, or fall away. After feeding and overwintering, the beautiful adult beetles emerge from the trees (probably from March through June in our area) creating a D-shaped exit hole approximately one-eighth inch in diameter. Once affected, ash trees decline quickly, often losing large limbs in the upper canopy. The tree’s death is caused by the widespread destruction of the phloem tissue supplying carbohydrates and dissolved nutrients.

 

For updates, additional information, or useful resources on EAB, please visit:

Texas A&M Forest Service:  https://tfsweb.tamu.edu/eab/

United States Department of Agriculture:  https://www.aphis.usda.gov/aphis/ourfocus/planthealth/plant-pest-and-disease-programs/pests-and-diseases/emerald-ash-borer

Bartlett Tree Experts Technical Report: https://www.bartlett.com/resources/technical-reports/emerald-ash-borer

Live Oak Tree

Live Oak Tree

Unique Trees of North Texas:

Live Oak

(Quercus virginiana or Quercus fusiformis)

 

By Eugene Gehring

You may be asking how one of the most popular and common tree species in North Texas could be considered unique. The fact that it is so popular and common is one of the reasons I think it is unique. Live oaks will grow in almost any soil type. Quercus virginiana (coastal or Southern live oak) is native from Virginia down the Atlantic coast to Florida and across the southern states to somewhere west of Houston. Quercus fusiformis (plateau or escarpment live oak) is native west of I-35 down into the hill country and North in a 3-5 county band to just north and west of Fort Worth. Live oaks are found in the transitional counties. Whether they are “Southern” or “Escarpment” is a good question. The primary morphological difference is the shape of the acorn. The escarpment live oak acorn is fusiform, or more constricted at the base. After 30 years working with live oaks, I still don’t have a clue what that means.

branching pattern

Live oak typically have long, extending branches that give the tree it’s unique shape.

Live oaks are different from the other oak species in several ways. They are evergreen or semi-deciduous. They drop their leaves in February/March instead of the fall. Their leaves are simple nondescript ovals, 1-4” long with an entire margin. White oaks have rounded lobes, while red oaks have points or stipules on their lobes. Based on leaf morphology, live oaks fit more with the white oak group. Live oaks can be more than twice as wide as they are tall with long graceful branches. White oaks tend to be about as wide as they are tall, and red oaks tend to be taller than they are wide.

The wood of most oak species is ring-porous. They lay down different size vessels and cells depending on the season. Live oaks are diffuse-porous. There is not a seasonal variation in the size of the vessels or cells. One of the major differences between white oaks and red oaks is tyloses within the vessels of the wood. In white oaks tyloses occur naturally, while in red oaks they do not. That is why whisky barrels are made of white oak. Live oaks do not have tyloses naturally in their wood, putting them in the red oak group.

Unlike most oaks, live oaks are prolific at sprouting from their roots. This characteristic, along with readily forming root grafts, allows live oaks in a given stand to share their roots. This is one of the reasons live oaks are considered drought hardy. It is also why oak wilt is so devastating to live oaks. During the drought of 2011 – 12 I witnessed live oaks in the Hill Country that bloomed or tasseled in the spring of 2011, but did not leaf out until it rained in the fall of 2012.

Live oaks have a unique ability to adapt and grow in a variety of environments. The exception being they do not tolerate extended periods of saturated soils. They will grow in the 100 year flood plain, but not in areas subject to regular flooding or standing water. In the late 1990s, there was a flood event on Lake Travis where mature live oaks were almost completely submerged and survived because it was a short duration. The same event killed live oaks on Stillhouse Hollow Lake because the water was not lowered as quickly.

large live oak in cemetery

Live oak growing in an old cemetery. Although live oak can live an extremely long time, they also grow rapidly when young which often leads to the age being overestimated. A live oak can grow to over 20″ diameter in just 30 years.

Live oaks are hardy to the 7b/8a zones of North Texas. I think the escarpment live oak is somewhat hardier than the Southern live oak. The 60 degree swing in temperature in January 2108 caused damage to the leaves on some live oaks in North Texas. They were not prepared for the extreme change in weather. When I first moved to the DFW metroplex, I was told there were live oaks with basal cankers caused by the cambium freezing during one of the cold winters in the 1980s.

Another unique characteristic of live oaks is that they will grow in almost any soil type. They thrive equally well in the sandy acidic soils of East Texas and the alkaline limestone based soils of Central Texas. Although they are not native to the heavy clays of most of North Texas, they grow and thrive there as well.

Climate change is probably responsible for the split between Southern live oak and Escarpment live oak. At a warmer period in time water covered a lot of North Texas as evidenced by ammonite fossils in Parker County. As the climate cooled and the water receded live oaks were pushed south and the split occurred.

Live oaks have long been valued as landscape trees. Some of the oldest planted can be found at Oak Ally Plantation in Louisiana.  They were thought to have been planted around 1710. In North Texas, they can be found in almost every neighborhood. Most of the older planted live oaks are probably Southern live oak because they would have come from nurseries in East or Southeast Texas. As the population in Central Texas increased, more tree nurseries were started in the 70s and 80s resulting in more escarpment live oak in the industry.  That is not to say there were not wild trees dug in Parker or Hood counties and planted in Fort Worth or Dallas. There were also nurseries, like O. S. Gray in Arlington, that may have grown escarpment live oak.

A little known fact is that live oak was used in the construction of the USS Constitution (“Old Ironside”). Live oak branches were used to form the ribs of the ship. They used the natural curves of the branches for added strength.

I have had a love/hate relationship in the more than 30 years I have worked with live oaks. I have seen them survive the extremes of drought, flood, tornadoes and hurricanes. I have seen them growing in practically solid rock, sugar sand, black gumbo clay, from East Texas to Midland/Odessa, from Lubbock to Houston to Corpus Christi. More than half of the trees in “The Famous Trees of Texas” are live oaks. The species has been witness to treaties, hangings, fights, marriages and everything in between. I think live oaks are unique because of their strength, adaptability, and mystic.

Eve’s Necklace Tree

Eve’s Necklace Tree

Unique Trees of North Texas:

Eve’s Necklace

(Styphnolobium affine)

Eve’s necklace in a North Texas landscape

 

By Susan Henson

This is a unique spring bloomer that has been underutilized in the urban landscape. It is an attractive small tree that can be used under power lines, grows well in shade or full sun, plus blooms pink, fragrant, and wisteria-like flowers in the spring (March, April or May). The seed pods look like the old pop string pearls which help provide year round interest. Could be used as a replacement for Crape Myrtle and creates an impact when grown alone. Eve’s Necklace is a legume and since discovering the roots lack nitrogen fixing bacteria the name was changed from Sophora affinis to the current Styphnolobium affine.

Eve’s Necklace has lustrous green leaves, scaly reddish brown bark, and a rounded crown with yellow hard, dense sap wood. The yellow sap wood is used to make yellow dye. It grows quickly when young and can grow to 6 feet from seed in 3 years. When planted in a sunny location it reaches 15 feet in height quickly and then crown becomes more rounded and the growth slows. When grown in dense shade will become spindly to the point of looking almost vine like reaching for the sun. It is related to the Texas Mountain Laurel (Sophora secundiflora) which is evergreen. Leaves are divided into 6 to 8 pairs of leaflets plus a terminal leaflet on a rachis up to 9 inches long. Leaflets are elliptic to oval averaging an inch long, with a rounded, indented, or pointed tip, with smooth margins, and a rounded tapered base.

Eve’s Necklace in Llano County, TX. This tree is far larger than individuals found in North Texas.

This tree thrives in the North Texas area on clay, sand, or limestone but the area should be well drained. The tree is native to Oklahoma, Arkansas, Louisiana, North Central and Central Texas. Once established this tree is extremely drought tolerant and only requires occasional watering. Can grow to 35 feet but have never seen it grow above 20 to 25 feet in height. In the wild it is usually an understory tree but can be found growing in roadsides, prairies, plains, meadows, pastures and open woodlands. Though short lived at 25 years they are easy to grow from seeds or cuttings. The bark is rather thin so particular care needs to be taken to protect young trees from weed trimmers.

The National Champion resides in Real County and is 37 feet tall, 77 inch circumference, a spread of 47 feet and an index rating of 125. There are specimens planted in Fort Worth as street trees on the north side of Park Hill between University and McCart, Turner Park in Grand Prairie, the campus of SAF under the power lines along the coliseum parking lot, San Antonio Botanical Gardens. The specimen in San Antonio Botanic Gardens is named ‘Amy’ and has a dark burgundy flower. The flowers can range from white to burgundy but are usually a lighter pink. This tree should be planted more in the DFW area.

 

Eve’s necklace leaves and flowers