Native Plants for Native Birds: Chestnut Oak (Quercus primus)

- By Joel Baines, Photos by David Ruppert

I will admit to an irrational appreciation of plants that eke out a living under difficult conditions. With little attention, Chestnut Oak will grow happily on steep dry slopes full of rocks. This habitat is regionally common, as it makes up the rims of the gorges around Ithaca and the surrounding Finger Lakes region. Similar habitats exist on the southern faces of the Catskill and Appalachian mountains, where the tree is also found. The range of this oak in the United States is quite limited and strictly eastern. North to south, the tree grows naturally from slightly north of Ithaca to the mountains of northern Alabama and Georgia, with peak sizes reached near the middle of its range in the mountains of Tennessee and the Carolinas.

Chestnut Oak is easy to distinguish in our area because of the foliage which barely looks like an oak leaf at all. There are no well separated lobes for example; instead, each leaf is heavily veined with the divisions between lobes only shallowly penetrating from the margins. The leaf shape is virtually identical to that of another excel- lent wildlife tree called Swamp White Oak (Quercus bicolor), except that the latter’s leaves have white undersides. The two trees can be distinguished by habitat as well—Swamp White Oaks live in the bottom of ravines rather than at the ridge top. Chestnut Oak is also smaller at maturity, reaching 60–80 feet, with a thicker brown bark. Several 20-foot specimens were planted along the river walk (appropriately, above the gorge rim) in downtown Ithaca where Green and State streets merge.

Chestnut Oak produces some of the largest acorns of any North American oak but does so only every 4–5 years. These acorns are more resistant to drying than those of most other oaks and are important wildlife food for a variety of mammals, Wild Turkeys, Blue Jays, and many other birds once the acorn is cracked open. These acorns also have a good germination rate (over 90%) when not attacked by weevils.

Because big acorns do not travel far in the wild, each seedling waits patiently near its parent for an opening in the canopy to shoot up when light becomes available. The growth rate of Chestnut Oak depends on the site but is similar to the growth rate of White Oak (Quercus alba) and slower than Northern Red Oak (Quercus rubra). From seeds, growth is dismally slow in full shade (6 inches in 10 years) but reasonable in full sun (around 6 feet in 10 years). In clearcuts, the trees sprout from stumps to 20 feet in 10 years. Acorns are produced when a tree grown from seed is about 20 years of age, but sprouts from cut stumps can produce acorns in as little as three years after cutting. Chestnut Oak saplings are easier to transplant than Northern Red Oak because the taproot of the Chestnut Oak seedling disintegrates as the tree grows, and the remaining roots form a dense mat about three feet deep. Twenty- foot saplings, although expensive, are available from some nurseries and usually transplant successfully. Although located on gorge rims in the wild, this does not preclude the gardener from planting these trees in more ideal sites where they will thrive, the only limitation being that the site must be well- drained. On the other hand, tough, dry sites promote more branching and less height, which to me, is when Chestnut Oak takes on its unique character, as the resulting squat appearance conveys a sense of ageless sturdiness.

Like most oaks, the plant is susceptible to deer browsing but will resprout once past the seedling stage. Resprouting commences the following year and even in the same season on good sites. Gypsy moths view Chestnut Oak as a preferred food plant and will sometimes defoliate the tree in midseason. Although this defoliation may temporarily weaken the trees, they usually recover as long as there is not a repeat performance in the same season. Otherwise, the trees are tough and resilient. If you have a rocky dry site where little else will grow, try Chestnut Oak.