62. Water Oak

Specimen Size: 79.4ft tall, 42.3in in diameter.

Location: At the south west corner of Architecture Hall, between it and the Population Health Center.

Historical Background: The magnificent Water Oak specimen at this location is the largest of species planted on the campus, with several others scattered around the grounds. Unlike most oaks, Quercus nigra is a tree which often lives fast and dies young, growing rapidly in its early years and reaching reproductive age early (about 20 years old), before perishing within the span of a human lifetime. Drought, disease, and insects are often implicated as the causes of this decline, but perhaps in this temperate location far to the northwest of the trees native home range, our campus Water Oaks may have a chance at an extended lifespan. The fast growth of the species, about 24 inches per year for the first quarter century, does have its benefits. The species has been used with success for restoring bottomland sites to a forested state, and has value as a short rotation timber species, where its wood is similar to that of other red oaks. It is also popular as a firewood. In landscaping scenarios, fast growing trees are often beloved by planners and developers, and despised by those who maintain the trees in maturity. Such fast growing species often have weaker wood and are more prone to losing branches or toppling entirely, and thus are vilified by many groundskeepers and arborists, although planting them in contexts where this is not an issue does provide an excellent large tree very quickly in a cultivated setting.

As with other oak species, Q. nigra is an exceedingly valuable wildlife tree, supporting a plethora of wildlife with its acorns in its native range, as well as a cadre of insects. As a tree susceptible to rot damage, Water Oaks also act as an excellent habitat tree, providing nesting locations for a variety of woodpecker species as well as the birds which take over these nesting cavities once they are abandoned by the original inhabitants.

Non-Native

Native Range: Southern United States and Eastern coastal plain. This species thrives in habitats which flood regularly but drain quickly thereafter, and enjoys levees, and swamp margins, as well as more upland sites which retain moisture throughout the year. While they can germinate in shade, they usually require a release from shade to grow beyond seedling stage.

Identifying Features: The leaves of this species exhibit fairly extreme phenotypic variation, meaning that they take on a wide variety of shapes, even on the same tree. They have a blueish-green surface with pale undersides, and are generally somewhat spatulate (like a rounded spatula) or lancelate (like the head of a spear), sometimes with 3 shallow lobes near the tip. The bark of the species is brown and smooth when young, turning dark and rougher with age. The fruit is an acorn, a nut tapering to a point and carrying a scaly cap. These seeds are relatively small as acorns go and very dark, rounded and about the size of a thumbnail. If identifying this species in its native range, recall that it generally prefers moist habitats. While the species usually features a slender tall trunk and rounded crown, our specimen here serves as a reminder that this is not always the case.

Identifying Features In Depth:

1. Form: A medium size tree usually achieving heights of 60-100ft (18-30m), with a symmetrical rounded crown and long slender trunk. 

2. Leaves: The shape of the leaves is more widely variable than almost any other species of oak in the region, from 2.5-6 inches (6.3-15.2cm) in length, and 1.5-2.4 inches (3.8-6.3cm) in width. Often shape is highly variable as well, generally spatulate, some are long and pointed like a willow leaf, while others have 3 distinctive lobes like that of the related Blackjack Oak. The surface is hairless, and a darker blue-green on top than on the underside. Though deciduous, these leaves remain far into the winter, and in mild years may persist right on through to spring.

3. Bark: The bark of the species is often quite dark in older age, almost black, but a light brown in younger years. It is smooth early in the tree’s life, but cracks into narrow scaly ridges when mature.

4. Reproductive Bodies: Acorns of this species have the classic acorn traits, a scaly cap and pointed tip. On this species, they are nearly black (thus the scientific name), rounded, and small (about 1.2cm long). The cap, or cupule, covers about ½ of the nut. Flowers, like on other oaks, are wind pollinated catkins which occur in spring and appear as long dangling bands.