The Sagacious Bur Oak.

Maybe when the bur oak is in full leaf, you can call it just a very large tree. In the winter though--when its structure and the almost knurled twisting of its branches are more evident--the bur oak is a show-stopper. This tree has character. It seems to say, "I've been around the block a few times and I have some wisdom for the rest of you, if you would just listen."

The rugged bur oak (Quercus macrocarpa) is forgiving as well. It tolerates poor soils; wide soil pH ranges; and, with its extensive root system, serious drought conditions. It cannot, however, tolerate repeated flooding.

Able to live 200 to 400 years and named for its bristly husks, or caps, bur oak goes by the names prairie oak, blue oak, scrub oak, or mossycup oak. It resides in the wild in deep rich bottomlands, where it attains a large size, and on dry ridges and western slopes, where it grows small and gnarled.

The tree grows across the eastern United States as far west as Montana and western Texas, with its native range extending to the foothills of the Rockies, where it is typically reduced to a shrub.

Bur oak has a history of adapting to take advantage of its space. Its relatively thick, fire-resistant bark and natural resistance to drought allowed it to compete successfully with prairie grasses. In pioneer days, many an unfortunate traveler in need of a new wagon tongue, wheel hub, or spoke sought out the bur oak, groves of which were also viewed favorably as home sites for early settlers in Iowa and other prairie regions. Today bur oak is the state tree of both Illinois and Iowa.

DESCRIPTION

When you plant a bur oak, leave it plenty of room. These shady beauties can grow 50 to 80 feet tall with an impressive canopy spread of 40 to 100 feet. The thick bark is dark gray and deeply furrowed, breaking into distinct ridges.

The leaves are 10 to 12 inches long and half that wide, large with rounded lobes. They grow alternately along the stems to some, the shape suggests a bass fiddle. The leaves are dark shiny-green above and lighter green to gray below. Fall color is yellow-green to brown.

Bur oak flowers may appear on old or new wood, often just as the leaves unfold. Buds of up to 1/4 inch appear in fall, covered with fine, pale gray hairs.

One of the tree's most spectacular features must be its acorns, which at 3/4 to 1 1/2 inches long are the largest of all native oak acorns. Almost round, they have a bur or mosslike fringed cap that covers at least half the nut--sort of an acorn with a bad hair day. It usually takes 7 to 10 years for a bur oak to produce its first acorns but the nuts mature in a single growing season and sprout soon after they drop in autumn. They can send a taproot 4 feet deep in the first year.

A mature bur oak might produce 5,000 acorns in a year with this heavy production every three to five years. After birds get their share, squirrels and other acorn lovers hoard what they need, and insects such as weevils finish up the feast, only 25 to 50 might actually sprout, and fewer than half make it to maturity.

The wood is hard, heavy, and strong with an interior color that varies from off-white to light brown. Because it is flexible and waterproof, the wood is appropriate for barrels and boat-building, and its high density makes it an excellent firewood.

USE IN THE LANDSCAPE

A bur oak can be magnificent on new home sites with plenty of growing room. Unfortunately, homeowners often unwittingly harm the bur oaks by removing moisture-retaining natural leaf mulch and replacing it with thirsty lawn grass, causing permanent dehydration.

Remember that virtually all the bur oak's feeding roots lie within the top 4 to 6 inches of soil--exactly the same area occupied by turfgrass roots. A tree living in turf can't compete for food and may live only half its life expectancy. Instead, surround the trunk with non-competitive groundcovers.

With its tolerance of site and soil--including the classic urban conditions of polluted air--bur oak is a terrific choice for industrial campuses, institutions, and parks.

WILDLIFE

In its natural setting the bur oak is valued by wildlife, which seem to prefer acorns from the white oak group, to which it belongs, as did Native Americans and early settlers. (The nuts' palatability appears to be inversely proportionate to the amount of tannin present.)

The tree is home of fox and flying squirrels, blue jays, turkey, grouse, and wood ducks, and serves as a launching pad for many kinds of hawks and owls. Its acorns feed various songbirds, upland ground birds, water birds, deer, wild turkeys, and many small mammals. Forests of bur oak serve as breeding sites for numerous songbirds, including indigo bunting, vesper sparrow, and yellow-throated vireo, which breed in these areas exclusively.

Because they are rich in carbohydrates and fats, the bur oak's acorns are the number one "fruit" consumed by wildlife. Its abundant foliage hosts insects favored by valuable songbirds, and birds and rodents play an important role in dispersing the acorns to new sites.

PLANTING A BUR OAK

Spring is the best time to plant these: fall is the next best. Give them full sun to thrive and don't plant under power lines or too close to the house. Once it's in the ground, don't plan on moving it later. After the tree reaches 6 to 8 feet tall, it becomes difficult to transplant because of its strong top root. An interesting conclusion now being drawn by arborists is that the tap root actually disappears as the tree matures in its 20s and 30s. That leaves the job of keeping the tree upright to massive stabilizing roots.

The size of a bur oak's root system depends on its environment. In sandy soils it can extend as far as seven or more times the drip area of the crown. In tight or wet soil, the roots may extend to the drip line or less.

Grown from seed the trees will reach 20 feet in 10 years. If you plant one that is already 4 or 5 feet tall, it will attain that same height in six or seven years.

TREE CARE

It is important in the early years to keep a 2- to 4-inch layer of organic mulch under the tree as far as the branches extend. Never pile mulch against the trunk. Pruning is necessary only if there has been storm damage or if some branches grow across each other and touch. To minimize the possibility of oak wilt, never prune between April and July.

PESTS

Bur oaks are tough trees with few serious insect or disease problems. Gypsy moths can attack bur oak; oak lacebug can turn the leaves off-color, causing long-term stress that heavily defoliates bur oaks in shelterbelt plantings, especially during dry weather. Several types of galls are frequently found on leaves and small branches but, while unattractive, cause little damage.

Bur oaks have good resistance to both oak wilt and to borers but, when growing conditions are not ideal, can suffer from anthracnose, "witches' broom," and other fungal diseases. Like other small saplings, their tender bark is vulnerable to rabbit and deer damage.

We no longer need bur oak groves to act as safety nets for Conestoga wagons heading west. But in this early stage of the 21st century, the bur oak still serves important ecological needs. If offers a very special piece of landscape architecture for those patient enough to wait for it to gain its look of wisdom and age.

Jeff Ball appears on NBC's Today Show as a gardening expert and writes books and articles on gardening. He also writes online for yardener.com.

THE NATIONAL CHAMP

Species: Bur oak (Quercus macrocarpo)

Location: Paris, Kentucky 

Circumference: 322 inches

Height: 96 feet

Crown spread: 103 feet

Total points: 444

Nominator: Owen H. Robinson

The National Register of Big Trees is sponsored by The Dexey Tree Expert Company.

OF POLITICS, ACADEMIA, AND TAIL TALES

As the politicians jet form town to town this summer "stumping" for votes, consider where that term came from. An oration used to be an afternoon's entertainment, so a traveling politician would have a tree cut down and present his "stump speech" while standing on the base.

One warm day in 1857, several hundred townspeople in San Marcos, Texas, gathered under the spreading branches of a bur oak to await the arrival of Sam Houston. The U.S. senator and charismatic here of the battle of San Jacinto was running for governor, and his speeches were popular as both politicking and entertainment

Upon Houston's arrival a group of women presented him with a hand-made Texas flag and he, in turn, bestowed kisses on them. Ever since, that massive old tree has been known as the Kissing Oak, and it remains as impressive as the hero who provided its name. It also produces acorns bigger than golf balls.

Bur oaks have always seemed friendly to me, with the spread of their sheltering branches often rivaling their height. One of my favorites grows on the campus of my aim a mater. Vanderbilt University, in Nashville. The massive Vanderbilt Bicentennial Bur Oak bears a plaque declaring it to be at least 250 years old--a mature tree at the time of the American Revolution.

Were I to rename it. I'd call it the "dreaming tree." It stands just outside the campus dining hall, and generations of students (myself included) have eaten beneath its spreading branches, dreaming dreams. I remember the sculpted leaves unfurling, a sure sign of spring, the full, proud coat of green worn throughout the summer, and the blaze of orange and yellows that announced the end of fall. But I loved that tree most when it was barren of leaves, for then I could lay on the ground and look up, seeing how those mighty branches pierced the sky, a bridge between heaven and earth.

Perhaps it won't surprise you to hear that I gathered acorns from that tree, and one of its descendants grows even now outside my office window.

There's another bur oak that gives me a shiver every time I think of it. Long before Harry Potter, Mary Twain entranced readers with the hair-raising adventures and antics of Tom Sawyer and Huck Finn. I loved those books when I was growing up, especially the scary parts. And noting was scarier than when Tom and Becky got lost in the cave and what Tom discovered there.

Samuel Clemens (aka Twain) grew up in Hannibal, Missouri, and many of his fictional locates and characters are based on local places and folks -- including that famous cave.

Simms Cave, discovered there in 1832, became a place of fascination for local children. A huge old bur oak guards the entrance to Simms Cave, and I like to imagine Clemens and his friends lounging in the tree, spinning dreams on a lazy summer afternoon. Today Simm's Cave is known as the Mark Twain Cave, the tree as the Mark Twain Cave Bur Oak (at center).

These three trees are all part of America's living history, history that can continue in your backyard. Descendants of these bur oaks are available from the Famous & Historic, Trees program. For more information, call 800/320-TREE.

Jeff Meyer, Director, AMERICAN FORESTS' Famous & Historic Trees project

Help AMERICANS FORESTS plant bur oak this year at four Global ReLeaf sites--in Kentucky, Minnesota, Texas, and Wisconsin. For information: www.americanforest.org. Every $1 plants a tree.