Scientific Name
Quercus nigra
Water oak has a native habitat very similar to that of willow oak: from east Texas in an arc through Georgia and up the coast to New Jersey. It is most often found on wet ground but has the capacity to adapt to dry planting sites as well. It has a different ecological behavior, however, often acting as an early succession tree on disturbed land, and it does not live nearly as long as other oaks, with 75 years or so being a typical life span. It also has a reputation for weak wood that can be prone to breakage during storms, and for that reason it is not typically favored for urban planting. However, it does have a few positive attributes: it is fast-growing, can have good late fall color, and can perform well on sites where other trees struggle.
Water oak leaves vary considerably. On mature trees they are usually unlobed and wider at the tip, resembling spatulas and often compared to a duck foot. On young trees and vigorous sprouts, they may have two or four lobes. They may also be unlobed and narrowly shaped, or resemble small red oak leaves. Water oak acorns are small, usually about ½ inch or less, and require two growing seasons to mature.
Water oak is even less common in our region than its native counterpart, willow oak, so it is not easy to estimate its mature size here; 35 feet may be a provisional estimate. Its cold hardiness is also not fully established. Minus 10°F has been considered a possible threshold, but that estimate was also applied to willow oak, which has since proven more tolerant. For now, it is best to continue experimenting with this tree within the Denver city limits, where conditions are slightly warmer than in surrounding areas.