In the Garden: Ragged Oaks

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Mr. Kidder and the 473-year-old Airlie Oak in Wilmington

As autumn leaves fall, the bare bones of deciduous trees are laid bare. We can now marvel at the sturdy structure of the oaks.

Oaks (the genus Quercus) comprise about 400 species widespread throughout the northern hemisphere. Although Mexico is actually the hotbed of oak diversity with 150 species, Virginia’s two dozen are a good mix of northern and southern representatives. Even if you can’t make room for an oak in your landscape, they’re worth admiring elsewhere, be it in your neighbor’s yard on a drive up to the Blue Ridge or even in more far-flung locales.

Oaks Around the World

Oaks occur in all the lower 48 states, southern Canada and down into northern South America.  They range over most of Europe, through North Africa, and on into Asia, being particularly abundant in Japan and China.  With their broad range and overall abundance, I’d hazard a guess that many people would respond with “oak” when asked to name a tree.

The genus Quercus can be divided into five major groups, but only two of these occur in eastern North America. The white oak group has leaves that have rounded ends on the lobes, whereas the red oaks have pointed tips, or bristles, on the lobes. The two groups also differ in the time it takes for their acorns to mature.

Oaks rank among the most useful trees. The strong wood has gone into countless ships, floors and furniture, as well as into barrels for wine and whisky. The bark of the Mediterranean Quercus suber can be peeled off to provide cork. Acorns furnish food for birds and many mammals, including humans. Although many species have very bitter acorns, others have relatively sweet meat, especially following treatment. Oak flowers aren’t generally considered ornamental, although the golden-yellow male catkins are conspicuous when the leaves first flush out. For most of us, shade and beautiful foliage would rank number one among oaks’ desirable traits.

Oaks in the South…and also in Your Landscape

Occurring throughout Virginia, I’d hazard a guess that oaks are our most abundant tree genus.  Among all these, the white oak (Q. alba) may well be the archetype of oaks, with its conspicuously lobed leaves and broad, spreading crown. Although the tallest white oak tops out at 144 feet, most growing in the open will have a spread greater than their height.  While they can live for hundreds of years, they’re not totally undemanding trees. Urban conditions present a challenge, especially compacted soils or fill dirt piled on top of their roots. You wouldn’t typically expect to find these problems in a rural area, but they can occur in new developments where heavy equipment has been used extensively for grading.

The red oak group is generally more suited to planting in the average landscape, since many of these species have a more fibrous root structure. The northern red oak (Q. rubra) has leaves with relatively shallow sinuses (the indentations between the lobes), grows rapidly and may develop respectable fall color. Another commonly planted oak in this group is the pin oak, Q. palustris. Its glossy leaves are relatively small and deeply lobed, giving the tree a finer texture than many oaks. Pin oaks can also have good red autumn color; as with all oaks, this is a highly variable commodity, so look at the tree in the fall if this is important to you.

Just to confuse matters, another tree, Q. phellos, also goes by the name pin oak, especially in the Deep South. Around here, it’s more commonly called willow oak, since the long narrow leaves lack any indentations and resemble those of some willows. The foliage gives the willow oak the finest texture of any of the genus, allowing it to blend into any setting. In Albemarle County, we happen to be at the western edge of willow oak’s native range; it occurs in the wild only farther south and east. Nonetheless, willow oak is widely planted, owing to its ability to tolerate a variety of conditions; witness the ones that have endured for decades along Charlottesville’s downtown mall.

We’d be remiss if we did not look at the oak named after this state, Quercus virginiana.  Despite the scientific name, the live oak is not common in the Old Dominion, reaching the northern limit of its range in the Hampton Roads area. The name live oak is actually applied to several species, all nearly evergreen, that inhabit the South, as well as the west coast of the U.S.

Truly an iconic tree of the Deep South, the live oak is typically depicted festooned with Spanish moss. It can reach gargantuan proportions, although to see it that way, you have to travel farther south. Large live oaks can be seen around Wilmington, North Carolina; Charleston, South Carolina, and on south. The Airlie Oak, at the gardens of the same name in Wilmington, appears in the accompanying photo

If you want to see an impressive live oak without leaving Virginia, visit the Emancipation Oak on the campus of Hampton University. With a spread of 98 feet, it was named one of the Ten Great Trees of the World by the National Geographic Society. Under its great limbs, the Emancipation Proclamation was first read in the Confederacy in 1863.

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