Well, hello. My name’s Ken Farr. I’m a dendrologist with the Canadian Forest Service
of Natural Resources Canada. And today we’re here in the Arboretum of the Central Experimental
Farm here in Ottawa to look at trees. And what we’d like to do is select some trees
that you might find useful for planting in the urban forest in and around the place where
you live. The interesting thing about the Arboretum
is that there’s a range of very old trees and much younger trees. And of course, they
come in a range of sizes, which is important for consideration if you’re going to be
planting trees in an urban area. We’ll also be talking a bit about how to identify trees
and some of the reasons why certain trees are more useful and more common in urban forest.
So I hope you’ll enjoy the tour. A good way to look at over 180 different exotic
and native tree species would be simply to download the NRCan Canadian Forest Service
smartphone app called “My Tree.” Using that app, you can simply enter your location
and you’ll see a list of tree species that are possible choices for where you are.
The Arboretum is a collection of trees that have been selected from native and exotic
specimens. It was originally designed to test how trees would grow at a relatively northern
latitude here in Ottawa, in central Canada. And so there’s an interesting selection
of trees that we can look at today, although we’ll focus on some of the more common trees
that you’re most likely to find at nurseries and in the landscape around you.
This is a very interesting selection for an urban forest tree. It’s called a Ginkgo
biloba, and it’s actually much older than the other trees here in the Arboretum by a
good hundred million years. And it’s also a very easy tree to identify based on the
shape of the leaves. It’s also called a maidenhair tree, which is a reference to a
maidenhair fern. So a fern kind of frilly, dichotomous leaves really quite different
than the other leaves on the trees we’ll see here in the Arboretum.
Why is it a good urban selection? The trees are very drought-resistant, heat-resistant.
They’re not affected by many diseases or by insects. And in fact, they probably existed
longer than the insects and diseases that might have attacked them in the past. So as
a selection for an urban forest or for a landscape around your house, it’s a fairly dependable
and safe tree to plant. Now, they’ll get much larger than this tree over a period of
time, but it takes about a thousand years for them to become really big. So it’s a
good selection for an urban site. One of the interesting features of ginkgo
trees is that they come in pollen-bearing and seed-bearing separate trees, and you won’t
often find fruit-bearing trees, fruit-bearing ginkgos — and it’s really not a fruit
at all — in the horticultural selection. When the fruit falls off the tree, it creates
a kind of an odour that is not particularly enjoyable. However, all of the trees — most
of the trees that are sold from nurseries and in horticulture — are pollen-bearing
trees. And then you don’t have that issue. So one of the few trees we’re going to look
at, that comes in Mr. and Mrs. Ginkgo.
So this is an eastern white pine, Pinus strobus. As the name suggests, it’s strictly an eastern
tree. It occurs in Canada, essentially from Eastern Quebec and in the Maritimes through
to about Lake of the Woods. But it’s also a standard urban planting across Canada in
terms of city selections for trees and shrubs. So why is it planted across Canada? It’s
a fairly dependable urban tree, except they’re prone to a drought at some points. They’re
a beautiful, fast-growing tree, and you can identify them on the basis of the needles
that are in bundles of five. So when you look at a pine tree, the needles — the leaves
— come in bundles of two, three or five. In the case of eastern white pine, they’re
in bundles of five. As you’ll notice from the form of the tree,
it’s very modular. There are no branches growing between the main rows of branches.
So you can effectively count the age of the tree by counting those rows from bottom to
top. In terms of size, they are very large trees
and you need a big space to plant them. So if you look behind this tree at the large
trees in the background, those are actually the same species, eastern white pine. And
they’re by no means as large as they’re going to get over a period of 200 to 400 years.
But you can see that, even at 70 to 100 years old, they do get to be quite big. So you do
need to think about space available for planting trees in and around your house. So eastern
white pine: an important tree in terms of the history of eastern Canada and the development
of the forests industry. And now a main component of the Great Lakes, St. Lawrence Forest and
fairly common as urban forestry as well.
This is a red maple, Acer rubrum. It’s one
of about 10 species of maples that grow in Canada, several of which show up consistently
in the urban forest. The one species you think of sugar maple, Acer saccharum, is actually
not a very good urban tree: it doesn’t do well in drought; it doesn’t like salt; and
it doesn’t like compacted soil, which is what one tends to find in urban sites.
The red maple is a fairly good urban tree more often than not. Now, you’ll find a
hybrid of silver maple and red maple, which is called a Freeman maple. But this is one
of the starting points for that hybrid, red maple. And it’s interesting in that this
is a fairly old tree. It’s probably a hundred years old or more. And you can start to see
the consistency of the bark, which is actually very characteristic from one species to another.
And this tree has long fissures, strips of bark that are loose at one end. As noted,
you’re not likely to see a tree this old in most urban landscapes and that have been
constructed more recently. But it gives you a good idea of how magnificent these trees
become with age and also how big they become. So as you can see from the foliage, a beautiful
red colour in the autumn — part of the reason it’s called a red maple. Also, the flowers
in the spring have red petals and the buds are red in the spring as well. So aptly named.
So, a red maple.
We’ve been talking about some of the more
regularly encountered and kind of basic tree species that you’ll find in an urban forest.
And there’s a reason for that, that certain trees will survive better and grow better
in urban conditions then others. However, over time it’s become apparent that it’s
necessary to mix up the list of species we’re using to avoid outcomes where you have too
many trees and Dutch elm disease — more recently, emerald ash borer. For that reason,
cities have been starting to expand the list of trees they plant in urban forests.
And this is a good example. This is a Kentucky coffee tree. It’s a native tree in Canada
to the Carolinian forest in the extreme southwest of Ontario, down around Windsor and Point
Pelee. But they’ve proven to be very adaptable trees. And, surprisingly, they grow very well
under urban conditions. So one of the interesting things about this tree is that it has, for
a broad leaf tree, it has the largest leaf of the native trees to Canada. The leaves
are compounds. So, one big central stalk and then smaller attachments with individual leaflets.
And this whole structure from here to here is a leaf, which is really quite interesting.
It’s another tree that grows as a fruit tree and is separate from pollen-producing
trees. The name Kentucky coffee tree is a reference to the fruit they produce, which
is a flat pod, just like a bean with what appear to be coffee beans inside, although
they’re nothing like coffee at all. These are becoming more and more common as
an urban tree. They’re fairly well suited to dry soils and hardy to about zone five.
So the Kentucky coffee tree, really an interesting new urban forest tree.
Another useful group of trees that you’ll find in the urban forest landscape are oaks,
and most people are able to identify an oak tree. Although identifying the species is
more problematic because there are many species to choose from. They divide up for the most
part into two groups: the red oak group and the white oak group. Red oak trees, having
pointed lobes on the leaves and pointed buds. The white oak group having rounded lobes on
the leaves and rounded buds. The tree we’re looking at here is in the
white oak group. It’s called a bur oak or Quercus macrocarpa. And that name refers to
the structure of the acorn, which is a nut with a cap on the top. And the cap has a fringe
of glands that make it look like a bur that gets stuck in your clothes, and hence the
name bur oak. A moderately large tree. They could get to
be 20 metres, 25 metres tall on an urban site, but moderately slow-growing as well. Nonetheless,
you need to think of the amount of space you have that can accommodate a tree that large.
To identify this tree is not terribly difficult. The leaves are really quite characteristic.
As mentioned, it’s in the white oak group, and it has rounded lobes on the leaves. But
in the case of this tree, you’ll notice that the central sinus between the lobes on
the leaf itself are very deeply cut, so that you have a upper part of the blade of the
leaf sort of divided from the lower part that’s towards the tree. That’s a fairly consistent
characteristic, although if you look through the leaves of any oak tree, you’ll find
there is a great deal of variety in their shape and size.
Another interesting feature of this tree — unlike most white oak group species that have scaly
bark. This tree tends to have long fissures with straight divides between them, and it’s
a little different than most of the other white oak trees, as noted. So bur oak, Quercus
macrocarpa, something I think you’ll see more and more often in the urban landscape.
Well, we’ve looked at a very short list of tree species today here at the Arboretum,
all of which are good additions to an urban forest. But it’s important to remember that
there are many more species that you might think about and many more than we can talk
about in the space of a short video. I’d suggest if you’re interested in more
kinds of tree species you can be using in a landscape that you visit NRCan’s Canadian
Forest Service web page and download the NRCan “My Tree” phone app. And there you will
find information on 180 native and exotic tree species — information on the growing
conditions that they favour and, most importantly, information on the hardiness zones where each
of these trees species will grow, understanding that climates vary across Canada and from
north to south. And it’s very important to plant trees in an environment where they’re
going to grow and survive.
So if you download that app and enter your location, it will give you a short list of
all of the species that will grow in your area or vice versa. You can enter a tree species,
and it will tell you if the tree will grow in your location or not.
And in closing, I’d like to thank you very much for joining us today in our walk through
the Arboretum. Thanks.
If you like this video, let us know with a thumbs up.
Click on the logo below to subscribe to the Simply Science channel,
and click the bell icon to be notified when we upload new videos.