Use of a plant identification key
A plant identification key is a tool to help you identify an unknown plant. To begin, the key gives you two descriptions and you decide which one best fits the plant you are trying to identify. Once you choose which description best fits, you are directed to two more choices and you repeat the process. If all goes well, your final choice will give you the name of the plant. You can then go to references such as books, local nurseries and/or the internet to look for descriptions and images to confirm your identification.
In order to work with a plant identification key, you will need to learn a bit of terminology as it applies to tree identification, so there is a learning curve. For this class, that is an important part of your experience. As you become more familiar with the terms though, it gets much easier. You will also find that the key gets easier as you get to know the trees.
The key is a shortcut. In order to identify an unknown tree, you could skip the key and look through a picture book to try and match your plant to a picture. There are some problems with this approach though: 1) you have to look through the entire book which is time consuming, 2) sometimes there are subtle differences between two species of tree, like the petiole length, which will not show up in a photo, and 3) you could be looking in a book that has pictures of trees we don't even grow here.
Just to get you started, let's identify tree number 1 from the Washington Park Map. I will pull excerpts from the Washington Park Tree Identification Key and walk you through the identification.
1a. Leaf typically 3/8 (0.95 cm) or less wide, leaf
shape scale-like, awl-like, needle-like, or narrow linear. ( Gymnosperms )
... 2
1b . Leaf typically 3/8 inch (0.95 cm) or more wide, not scale-like,
needle-like, awl-like, narrowly linear. Broad- leaf flowering plants ( Angiosperms )
and Ginkgo (Gymnosperm)
18
Looking at the leaves, they are less than 3/8" wide and either needle-like or
linear (plus I know its a gymnosperm from the lecture notes) so I would choose
1a and go to ... 2
2a. Leaf shape scale-like
3
2b. Leaf shape not scale-like
4
The leaf shape isn't scale-like, so I would choose ... 4
4a. Leaf shape awl-like
5
4b. Leaf shape not awl-like
6
The leaf isn't awl-like, so I would choose ... 6
6a. Leaf shape needle-like, arranged in bundles
(fascicles)... pine trees
7
6b. Leaf shape needle-like, arranged in clusters
on ends of short branchlets (cedars); OR narrow linear, arranged singly along
stem
11
These leaves are narrow linear and arranged singly along the stem, so I would
choose ... 11
11a. Leaf shape needle-like , leaves arranged in clusters at ends of short
shoots , cones upright on the branches ( Cedrus )
12
11b. Leaf shape narrow linear , arranged singly
along stem , not in clusters at ends of short branches, cones pendulant.
13
The leaves are arranged singly, and the cone is hanging down (pendulant), so
I would choose ... 13
13a. Cone pendulant, with three-lobed bracts between cone scales . Cones are
readily found on this tree
. Pseudotsuga menziesii , Douglas
Fir
14a. Leaf to 2 inches (5 cm) long and ¼ inch (6mm) wide, acute
point, somewhat stiff. Cone is fleshy and rarely seen
Podocarpus gracilior , Fern
Pine
Here's the cone with the three-lobed bracts between the cone scales which
are characteristic of the Douglas fir:
It looks like this tree is a Douglas fir, Pseudotsuga menziesii.
It was named after David Douglas, a Scottish plant explorer who died at the young
age of 35 in 1834 while climbing Mauna
Kea on the big island of Hawaii. He fell (or was pushed?) into a pit dug
to catch wild cattle which unfortunately had a bullock in it. Weather he fell
or was murdered is still a mystery.
ON TO MAP OF WEST HALF OF WASHINGTON PARK