Know Your Trees: Oaks

Today GM is going to continue his attempt to help you lose your tree blindness by teaching you a little bit about some of the mightiest trees around: oaks.

Oaks are one of the larger groups of trees that you might find on Georgetown streets. They range from towering giants to far more modest species. This list probably won’t cover every single variety you’ll find, but it will cover most.

The first thing to look for to identify an oak is acorns. But if it’s not the right season for acorns, look for the leaves. The basic oak leaf is fairly easy to identify. It looks like this:

Different variations on this basic shape distinguish between many of the more common oak species. But some oak leaves look nothing like this. They are identifiable by other features described below.

The first thing to say is that all oaks fall into two large groups: white oaks and red oaks. This isn’t really something you need to know to identify specific species, but it’s helpful in understanding how they break down.

White Oak

There are dozens of tree species within the white oak group. But only a handful of those are likely to show up in Georgetown. Confusingly, one of those species is called a white oak (which is different than the larger white oak group). Like the larger white oak group, the white oak species has rounded lobes like this:

White oaks are slow growing giants. Between this and their massive mature size, they don’t get planted in street tree boxes very much.

You’ll find white oaks in places like Dumbarton Oaks and Montrose Park (like the one in the photo on top by the playground). Given the right space, white oaks can live for centuries. Famous white oaks include the Charter Oak of Hartford, CT and the Wye oak of Talbott, Maryland.

Chestnut Oak

Another oak in the white oak group that you might find in Georgetown is the chestnut oak. It is not nearly as large as the white oak species. It’s leaves look like this:

Don’t get this species mixed up with the English oak (which has similar leaves), which will be described below. The chestnut oak has a typical canopy shape, the English oak looks like a column.

English Oak

English oak is popular oak species, with many varieties. But in Georgetown, what you see a lot are columnar English oaks. They, not surprisingly, look like a column, like this:

That’s the best way to identify them in Georgetown.

And that’s about it for white oaks. Most of the oaks you’ll find on the street in Georgetown are red oaks.

Pin Oak

The pin oak is easily identified by its leaf. It has pointy and skinny lobes, like this:

Pin oaks can grow quite large and tall for street trees. There is one on GM’s block that is at least 60 feet tall.

Beyond its distinctive leaf, what will also easily identify a pin oak is the fact they keep their leaves throughout the winter. The leaves turn red, then brown in the fall like a normal oak. But then the leaves don’t fall from pin oaks in the autumn, particularly with younger pin oaks. They look like this in the winter:

According to the city’s count, pin oaks are the second most popular street tree in the city, behind red maples.

Scarlett Oak

Scarlett oaks are also quite common in DC, although there aren’t that many in Georgetown. They have even skinnier and pointier leaves than the pin Oaks:

The difference is rather subtle between the pin oak and the scarlet oak leaves. The bark is more distinguishable though. Scarlet oak trees have a deeply ridged bark like this:

Pin oak trees have a smoother bark like this:

Ultimately it’s hard to distinguish the two. Scarlet oaks even can be known to hold on to leaves into the winter like pin oaks. So don’t worry if you can’t tell one from the other.

Willow Oak

Willow oaks are magnificent. And they are everywhere in DC, particularly the “leafier” parts of upper Ward 3. They grow to incredible heights for a street tree, with an equally impressive canopy.

And they are easy to identify by their leaf, which doesn’t look anything like a normal oak leaf:

They grow fast and once they get to massive sizes they can start to cause problems with the sidewalk. Despite this, and despite the fact that DC has already planted a ton of these, they are still planted anew in Georgetown.

There are certainly other oaks, but this should cover most you’ll find in Georgetown.


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