Water Oak (Quercus nigra)

Black Oak, North American Barren Oak, North American Black Oak, Oaks, Possum Oak, Water Oak

Water oaks are native to North America and found across the American South. These medium sized trees are ornamental shade trees and have an ease of care that makes them perfect in the landscape. Try growing water oak trees as street plants or primary shade trees but be aware that these plants are short-lived and can be assumed to survive 30 to 50 years. Read the article below for more water oak information.

I. Appearance and Characteristics 

Quercus nigra, the water oak, is an oak in the red oak group (Quercus sect. Lobatae), native to the eastern and south-central United States, found in all the coastal states from New Jersey to Texas, and inland as far as Oklahoma, Kentucky, and southern Missouri. It occurs in lowlands and up to 450 meters (1,480 feet) in elevation.

Other names include spotted oak, duck oak, punk oak, orange oak, and possum oak.

Quercus nigra is a medium-sized deciduous tree, growing to 30 meters (98 feet) tall with a trunk up to 1 m (3 ft 3 in) in diameter. Young trees have a smooth, brown bark that becomes gray-black with rough scaly ridges as the tree matures. 

The leaves are alternate, simple and tardily deciduous, remaining on the tree until mid-winter; they are 3–12 centimeters (1+1⁄4–4+3⁄4 inches) long and 2–6 cm (3⁄4–2+1⁄4 in) broad, variable in shape, most commonly shaped like a spatula being broad and rounded at the top and narrow and wedged at the base. The margins vary, usually being smooth to shallowly lobed, with a bristle at the apex and lobe tips.

The tree is easy to identify by the leaves, which have a lobe that looks as if a drop of water is hanging from the end of the leaf. The top of each leaf is a dull green to bluish green and the bottom is a pale bluish-green. On the bottom portion of the leaves, rusty colored hairs run along the veins. The acorns are arranged singly or in pairs, 10–14 millimeters (3⁄8–1⁄2 in) long and broad, with a shallow cupule; they mature about 18 months after pollination in autumn of the second year.

Water oak has been a source of timber in the American south since the 17th century, where it is often commercially sold as “red oak,” and mixed with other types of oak. It can also be commercially used to make fuel. Some species can undergo yellowing of the leaves, which is caused by an iron deficiency called chlorosis.

Water oak has the potential to cause toxic reactions if ingested, due to its nature as a member of the Quercus genus. If eaten, certain parts can cause mild to moderate symptoms. These parts include the young leaves and acorns, both of which contain toxic tannins. Eating these tannins can lead to such symptoms as upset stomach, constipation, bloody stool, diarrhea, extreme thirst, and excessive urination; at worst, the kidneys can be affected. Because oak trees are popular features in parks and yards, the leaves and acorns can be easily accessible to young children who might mistakenly ingest these toxic parts.

Water oak serves the same ecological role as weeping willow and other wetland trees. It is adapted to wet, swampy areas, such as along ponds and stream banks, but can also tolerate well-drained sites and even heavy, compacted soils. It grows in sandy soils, red clays, and old fields to the borders of swamps, streams, to bottomlands. Due to its ability to grow and reproduce quickly, the water oak is often the most abundant species in a stand of trees. The tree is relatively short-lived compared to other oaks and may live only 60 to 80 years. It does not compete well and does not tolerate even light shade. 

Water oak is frequently used to restore bottomland hardwood forests on land that was previously cleared for agriculture or pine plantations. Minimum age for flowering and fruiting is 20 years and the tree produces heavy crops of acorns nearly every year. Water oak is not recommended as an ornamental due to being short-lived, disease-prone, and extremely messy.

II. How to Grow and Care

Sunlight

Water oak should be planted in a field with full sun. It gives shade, shady plants can be planted under it.

Temperatures

Water oak grows in a large range of temperatures. It is adaptable in hardiness zones 5-9.It prefers well drained soil with adequate ventilation in the tree canopy. Water oak will not do well in standing water. Also, leaf molds pose serious threats if the leaves cannot dry out in the wind. So make sure they are not stuck against buildings where rainwater may drain.

Watering

Keep soil moist but well drained. Oaks form a taproot and will draw moisture up from below. So make sure there is humid soil if you dig down a few inches, but do not flood the topsoil. Reducing summer water use will make water oak more healthy, they tolerate summer dry spells very well.

Soil

Ideal soils are well-drained loam, sandy-loam, or sandy-clay soils. Some alluvial fan areas and silts harbor good oaks stands. The key in all of these is that the soil is well-drained. Standing water cannot be tolerated by oaks.

Fertilizing

Water oak can survive and thrive without supplemental fertilization. But if you wish to give them extra nutrients you can add some of 12-6-6 (N-P-K) fertilizer. This has more of a ratio of nitrogen than phosphorus and potassium. Also, consider the natural environment of oaks. They grow where there is lots of forest litter. This forest litter acts as natural mulch that breaks down into organic matter and humus. So one way to give some natural nutrition is to spread mulch by your oak trees. They will love the extra organic matter.

Planting Instructions

It may takes a very long time if you want to get a mature oak tree from an acorn. But with patience, planting a small tree is still fun. Be sure to kill weevil larvae by soaking the acorns in 41 ℃ water for 30 minutes, stratify in moist sand in the refrigerator (not freezer), and plant in the springtime.

Pruning

Branches should be pruned to avoid moist pockets or where heavy branches may fall on people or buildings. Avoid having branches that grow with leaves tight together or pressed against buildings. If rain collects in these pockets then molds and fungi can attack. Water oak love having their leaves dry out in a well ventilated breeze.

To ensure that no danger occurs from the brittle hardwood branches, make sure that heavy branches do not hang over walking paths or outbuildings. Also, do not let children play near oaks in a thunderstorm as they are susceptible to falling branches and lightning strikes.

Transplanting

Optimum transplanting time for water oak is during S1-S3 (late winter to early spring), when the plant is dormant and stress is minimized. A sunny or partially shaded location with well-drained soil promotes healthy growth. While transplanting, ensure to protect water oak’s sensitive root system.

Pests and Diseases

III. Uses and Benefits 

Uses

Water oak wood is relatively poor quality, so it is used as mediocre factory lumber. It is sold as red oak timber and used to make pulp, plywood, and poles. However, the water oak is an excellent shade tree that reproduces quickly, so it is more often used for landscaping. It has also been used for the restoration of bottomland hardwood forests in the southeast on land that was previously cleared for agriculture or pine plantations.

Many Native American tribes relied on the water oak for its medicinal value and for food. The galls on the tree are strongly astringent and can be used in treatment of hemorrhages, chronic diarrhea and dysentery. The seeds were gathered, dried, and then ground into a powder which was then used to cook stews or mixed in with cereals to make bread. The acorns were pounded into a mortar and boiled to make cornmeal, and the leaves were used to make mulch which repelled slugs, grubs, and such.

Water oak acorns are an important food for white-tailed deer, eastern gray squirrel, raccoon, wild turkey, mallard, wood duck, and bobwhite quail. In winter, deer will browse the buds and young twigs.

Historical and Cultural Significance

Because of its relatively limited usability, the water oak is not considered culturally or historically significant. However, the family of oak trees, containing about 600 species, has been symbolic throughout history. The Oak tree represents strength and endurance, and it is the national tree of fifteen countries, including England, Romania, France, Serbia, and the United States. It also appears in several historical myths and legends. In Greek mythology, Zeus, the king of gods, considered the oak tree sacred. By interpreting the rustling of the oak leaves, the priests would make the divine pronouncements of the gods. 

The oak was also sacred to many other gods including Thor, Jupiter, Dagda, and Perun. These gods, including Zeus, had dominion of the rain, thunder, and lightning, and they were associated with the oak because of its tendency to attract lightning. In Celtic mythology, the oak tree represented wisdom, endurance, and strength. It was used for the interpretation of dreams and increasing male fertility. According to Celtic legend, King Author’s round table was made of a single cross section of an oak, and each tree was a metropolis of fairies

Water Oak (Quercus nigra) Details

Common name Black Oak, North American Barren Oak, North American Black Oak, Oaks, Possum Oak, Water Oak
Botanical name Quercus nigra
Plant type Native Plant
Hardiness zone 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b
Growth rate Fast
Harvest time Fall
Height 50 ft. 0 in. - 80 ft. 0 in.
Width 50 ft. 0 in. - 80 ft. 0 in.
Sunlight Full sun (6 or more hours of direct sunlight a day)
Soil condition Clay
Flower color Gold/Yellow
Leaf color Blue