Monday, September 10, 2012

The pin oak

Species name: Quercus palustris

Common name: Pin oak

Location: Ontario

My friend Tanya demanded more native species in my blog, so here we go! Another native tree, just for Tanya. The pin oak is just barely native to Ontario; the native range extends only as far north as my hometown so I guess I should be considered lucky! The native range extends quite far south, as far as Georgia and all the way west to Oklahoma and Kansas. In Ontario this tree is relatively rare except where planted for ornamental value, and it's difficult to say what might happen with climate change. Species ranges are expected to move towards the poles (so in this case, north) but one also has to keep competitive ability in mind before you make those kinds of assumptions. The pin oak is an incredibly poor competitor, especially when it comes to shade and moisture. In the spring, during the seasonal flooding periods, the pin oak is incredibly tolerant of being partially submerged, and opts to set leaves later in the season once the ground is drier. During the growing season, however, the pin oak is very intolerant of standing moisture around the trunk, and any moisture at all towards the base of the tree often leads to severe decay. Unlike most other oaks, the pin oak doesn't have a large taproot that it uses for underground support; instead it has a very shallow root system that stretches over a large area. Once the bottom of the trunk is rotten, the tree no longer has a support system and it is prone to being blown over during any kind of severe weather. This tree is also very shade intolerant; even small shrubs can out-compete this tree for resources when young. It just doesn't seem to have the ability to push up out of the lower canopy, even though the potential height of this tree is 60 feet or more.

I guess this is the first blog post where I have to admit that my plant identification skills are sometimes aided just by the location that I'm in. My hawk-eyed blog readers will notice that there's a post coming out of the ground in front of the tree with an information plaque on the top. All of Western University's campus is an arboretum, which is basically an outdoor museum of living plants. It's not quite a botanical garden, since botanical gardens often have public greenhouses associated with them (we don't), but they also have ALL plants labelled to the species level. At Western, it's only the trees that have labels, not all plants. The label contains the common name, the species name, the family that the species is in, and soon will have information about whether or not the tree is native, and whether or not the tree is considered invasive. It's incredibly convenient being able to walk around campus and learn about plant identification; you can actually walk up to the trees and touch them, smell them, feel their bark, break open young twigs to see what colour they are, etc. It's also incredibly helpful to be able to see a tree through the seasons, which can also help with remembering names of trees.

But back to the pin oak!

The uses of pin oak are many aside from the ornamental value of this plant. The pin oak is actually one of the many reasons why we now have an entire field of work called "forensic botany"! Sometimes the pin oak is sold as lumber under the name "red oak," which as you know is a completely different species. If it stopped there, then I wouldn't really see a problem. But in reality the wood of the pin oak is much weaker compared to the red oak, has much less of a desirable colour and grain pattern, and has many, many more knots in the wood than a red oak would. Using this species in place of red oak could lead to disastrous consequences, depending on the intended purpose of the wood. The best use of pin oak wood is as firewood, or to make wooden pins for building construction (where the common name probably originates). It is also a medicinal plant, having been used historically in a tea used to treat intestinal and abdominal pain.