Quercus alba – White Oak

White Oak is the iconic, broad-limbed majestic oak tree of eastern North America.

White Oak grows at its northern range in Ottawa and West Quebec on south-facing uplands and along rivers.  These conditions moderate temperatures, extend the growing season, and help the acorns in some mast years to ripen to maturity.  There is speculation that this species was once more prevalent in the Ottawa Valley in its preferred microclimate locations.  When cut down it was outcompeted by faster growing northern species like Bur Oak and Red Oak, which grow more rapidly and fruit prolifically more often.

White Oak (Quercus alba) in Lanark.
White Oak in Lanark, Ontario.
White Oak (Quercus alba) near Guillot Park in Aylmer, Quebec.
White Oak near Guillot Park in Aylmer, Quebec.

It’s possible that the area along the Ottawa River called Deschênes Rapids (des chênes means “of the oaks” in French) was named for the proliferation of White Oak along the banks of the river.  The two remaining populations of  White Oak in the Ottawa area grow in this area:  by the river in Guillot Park at Deschênes, Quebec and on the opposite shore in Ontario at Britannia Conservation Area.

In Eastern Ontario/West Quebec White Oak grows in association with Shagbark Hickory (Carya ovata), which shares many of the same warm microclimate requirements at its northern range.

Identification

White Oak is most often confused with Bur Oak.  In the Ottawa Valley the term “white oak” is  sometimes used to refer to Bur Oak (Q. macrocarpa), which shares the same Quercus subgenera as White Oak (Q. alba), but they are very different trees.

  • White Oak has deeply lobed leaves while Bur Oak leaves, which can be  quite variable, are typically violin-shaped, broader at the tip and not as deeply lobed.
  • White Oak foliage emerges pinkish-green in the spring  and matures as reddish-pink in the fall compared to the light yellow-green and  dun brown respectively of Bur Oak.
  • In shade, the leaves of White Oak  seedlings often have a blue-green cast.
  • White Oak bark is quite  distinctive being pale and plated compared to the ridged and furrowed  brown bark of Bur Oak.  Some particularly tortured young Bur Oak  can mimic White Oak with pale, plate-like bark.  Look closely at the  leaves to distinguish them.
  • The White Oak acorn cup encloses less than half the fruit.  The cup of Bur Oak acorns encloses more than half of the fruit and is fringed.
Pinkish-green buds of White Oak (Quercus alba) in spring (O. Clarkin).
Pinkish-green buds of White Oak in spring (O. Clarkin).
White Oak in Eastern Ontario and West Quebec
Pale grey, plate bark of White Oak (Quercus alba) at Britannia Conservation Area.
Pale grey, plate bark of White Oak at Britannia.

The largest population near Ottawa is at the Britannia Conservation  Area on the west side.  Daniel Brunton documented these in the Ottawa Field Naturalist’s Club magazine Trail and Landscape (1997).  They grow there with other, more southerly species like Hackberry (Celtis occidentalis).

Farther  west of Ottawa, White Oak grows in sporadic stands on rocky uplands, often on  warm, sunny, south-facing slopes, in Pakenham, Calabogie, and on Blueberry Mountain in Lanark County.

On the Quebec side, White Oaks are scattered in Gatineau Park along the Eardley Escarpment, the Wolf Trail, and the Luskville Falls Trail.   The ravine and south facing slope locations on the Eardley Escarpment offer warmer, extended season growing conditions and likely some protection in the past from logging due to difficult terrain.  In one dry, upland location the oaks grow with Hackberry as they do at Britannia.

White Oaks are also found along the Gatineau River near Mont Cascade and along the Ottawa River at, appropriately, Pointe-au-Chêne near Grenville.

White Oak (Quercus alba) at Blueberry Mountain, Lanark.
White Oak at Blueberry Mountain, Lanark.
White Oak (Quercus alba) at Britannia Conservation Area.
White Oak at Britannia Conservation Area.
White Oak (Quercus alba) at Pointe-au-Chêne, Quebec (O. Clarkin).
White Oak at Pointe-au-Chêne, Quebec (O. Clarkin).
Growing White Oak

White Oak is slow growing and long-lived, so plant for future generations.  Once established it is extremely drought tolerant.  It needs full sun and a place where it can extend its roots deep into the soil and rock.  It will take well over 35 to 45 years to bear fruit, which are sweet and edible when raw.  Although hardy to Zone 4, it requires a sufficiently long growing season for these fruit to ripen.  Climate change is extending growing seasons, particularly with late fall frosts, and may improve conditions for White Oak and other borderline southern tree species.  It is self-fertile, but will bear more fruit if cross-pollination with other White Oak trees occurs.

Selected photographs with location coordinates in iNaturalist

https://www.inaturalist.org/observations/8197623 – Lobed leaves and plated bark in Aylmer, Quebec.
https://www.inaturalist.org/observations/8337328 – Mature oak, King Mountain Trail, Gatineau Park, Quebec.
https://www.inaturalist.org/observations/8197694 – Lobed leaves near Luskville, Quebec.
https://www.inaturalist.org/observations/5264284 – Red fall colour in Aylmer, Quebec.
https://www.inaturalist.org/observations/7684368 – Spring pinkish-coloured buds in Ottawa greenbelt near Kanata.
https://www.inaturalist.org/observations/32419827 – Blue-green leaf colour of seedling in shade at High Lonesome Nature Reserve.
https://www.inaturalist.org/observations/9465763 – Mature oak at Pointe-au-Chêne along the Ottawa River.

References

Brunton, Daniel F.  White Oak (Quercus alba) in Southeastern Ontario and the Ottawa District.  Trail & Landscape.  Volume 31, No. 3.  1997.  Pages 100 – 107.

Brunton, Daniel F. and LaFontaine, J.Donald.  An Unusual Escarpment Flora in West Quebec.  Canadian Field Naturalist.  Volume 88.  1974.  Pages 337 – 344.

Guillett, John M. and Catling, Paul M.  Gatineau Park:  Vegetation, History, and Geomorphology.  Trail & Landscape.   Volume 28, No. 4.  1994.  Pages 129 – 138.