Oak - Bur
OTHER COMMON NAMES: MOSSYCUP OAK, MOSSY OVERCUP OAK, PRAIRIE OAK
Quercus macrocarpa (KWER-cus mack-row-CAR-puh)
Fagaceae (Beech Family)
Deciduous shade tree
HEIGHT: 60 to 80 feet
SPREAD: 60 to 80 feet
FINAL SPACING: 30 to 50 feet
NATURAL HABITAT AND PREFERRED SITE: Bur oak is a resident of the tall grass prairie from north Central Texas to Central Texas. It will adapt to a wide range of garden and landscape conditions.
IDENTIFICATION INFORMATION: Bur oak is a stately, tall rounded, tree with huge leaves and, golf ball size acorns. The yellow fall color is so-so at best.
FLOWERS AND FRUIT: Rust-colored male flowers hang from the terminal growth in the spring. Female flowers bloom singly or in small clusters. Fruits are very large acorns, some are as large as golf balls.
BARK: Medium-textured, light to medium gray, sometimes developing a rough texture in spots even on some of the young branches. The terminal stems are quite large. The buds are also large and egg-shaped. Stems and twigs occasionally have wings or ribs.
FOLIAGE: Leaves are alternate, simple, very large from 6 to 10 inches, – sometimes 4 to 5 inches wide, rounded lobes. The fall color is yellow to brown and usually nothing to write home about. If this tree had good fall color it would be the perfect tree unless you don’t like big acorns.
CULTURE: Probably the easiest to grow of all the oaks. Bur oak is drought tolerant. And does well in many different soil types from sand to heavy clays. It grows well in the black and white soils of north Texas. It has very few disease or insect pests and the fastest growing and probably the longest living of all the oaks for Texas. It can grow up to 150 feet in height in deep soil.
PROBLEMS: Bur oak is occasionally attacked by lacebugs which turn the leaves a brownish color in the summer but that is always due to stressful conditions – too much or too little water, too much high-nitrogen fertilizer, not using the organic program, etc.
PROPAGATION: Plant the large acorns as soon as they release from the tree. If they lay on the ground any length of time at all, the insects realize how tasty they are and will get them before you can have any success. After putting the large acorns in the potting soil or in the ground, the only worry is to not let the soil dry out and to keep the squirrels from getting your little treasures.
INSIGHT: Probably my favorite shade tree and should be planted on any site where there is enough room. Overcup oak – Quercus lyrata it is often confused with bur oak but as opposed to bur oak’s ability to grow in calcarious and limestone soils, overcup oak grows only in acid, sandy loam and wet soils. It is almost always confined to swamps and other wet soil areas. Its other common names are swamp post oak, swamp white oak and water white oak.
The now famous bur oak in Waco, Texas. Owner Terry Hobbs is down in the hole that was created by removing almost 10 feet of fill from the trunk of the tree. It looks as if the beautiful tree will make it.
Waco Bur Oak
One of my most interesting radio show calls came from Terry Hobbs in Waco, Texas. Our conversation on the air led to one of the most interesting trunk flare exposure projects ever. Here’s the story in Terry’s words followed by a photographic review of the successful project.
We became concerned about the lack of leaves on my bur oak tree, which was estimated to be about 150 years old in the late 1990's. My wife called a local tree man and he came out and injected some chemicals into the base of the tree. It didn't seem to change the quality of the tree at all.
We were already following the Dirt Doctor and treating our yard with the organic materials. It was about 2003 when we learned about the need to keep for your tree flares exposed. So we began digging. When we got to 2 1/2 feet I decided to call the Dirt Doctor to see how far to dig. He said keep digging; there was a tree flare somewhere.
At that time I decided to hire a young man to help. We continued to dig. The tree had originally been on a creek bank that was replaced by a large culvert and covered over.
At 4.5 feet we uncovered the first flare. The next flare was uncovered at about 9 feet.
An attached picture shows the barrel I constructed as a retainer wall to prevent the wall caving in.
The work has been successful because the tree's condition has improved and the circumference has increased from 104 to 111 inches.