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Summer
2000
Name
That Plant
For
help in identifying plants in the field, turn to fellow
stewards and a copy of Plants
of the Chicago Region
by
Joe Neumann
At
6:00 p.m. we gather at a pavilion in the Palos division
of the Cook County Forest Preserves. Rich is waiting for
us. He is the recognized plant expert among the Palos volunteer
stewards. A large part of ecological restoration involves
removing aggressive non-native species. But a broad knowledge
of native species is essential for assessing the progress
of a restoration and for such tasks as collecting and scattering
seed. This evening Rich will be leading us in a plant identification
session.
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Photo
by Jerry Reedy.
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How
do you identify an unknown plant? A guidebook with drawings
or photos is a good place to start. Volunteer stewards have
another resource — each other. If you need to identify
a plant, you ask a fellow steward. One of them may recognize
it. Perhaps it grows at the site one of them works on. Or
perhaps one of them has an eye for its distinct features,
or was present when a botanist identified it.
The
third resource, and the final say in plant identification,
is Plants of the Chicago Region by Floyd Swink
and Gerould Wilhelm. This bible-sized book provides a deep
look into the intricacy of the ecosystem of the Chicago
region along with a complete listing of the 1,638 native
plant species and the 892 non-natives found here. Extensive
keys separate species on the basis of their technical botanical
characteristics. A write-up on each species includes information
on its ecological niche and sometimes a piece of its local
history.
We
learn there that just over 50 years ago tens of thousands
of fringed gentians grew in the vicinity of what is now
17th and Whitcomb Streets in Gary, Indiana. Today you could
buy gas there, but you’d be hard put to find a gentian.
The
"botanist’s method" is the one we will be
applying this evening. We congregate at a picnic table.
Plant samples poke out from the pages of each Swink &
Wilhelm. You can tell how serious a botany student a person
is by how many plant samples are pressed between the pages
of his or her Swink & Wilhelm.
We
spread our specimens on the table. Rich picks up a plant.
What is it? A grass? A sedge? A distinguishing feature of
sedges is that they are "3-ranked." Each leaf
along the stem rotates 120 degrees with respect to the one
beneath it. Count up from a lower leaf: 1, 2, 3, 4. The
fourth leaf lies directly above the first leaf you counted.
Grasses are "2-ranked." As we examine the sedge
sample further, Rich points out another feature that helps
separate one group of sedges from another. Is the seed "lenticular"
(two-sided like a lens) or "trigonous" (three-sided)?
Each
step of a botanical key presents you with two options. You
choose one, which leads you to another pair of choices.
In this way you repeatedly narrow the alternatives until
only a single species remains.
We
examine one of the sunflowers now and another plant that
is similar. This second plant is one of the Silphium family.
The tiny disk flowers that comprise the center of the sunflower’s
head will produce seeds while the petal-like flowers that
ring the center are sterile. For the flowers of the Silphium,
the reverse is true. Seeds form only on the sides of the
head — the petal-like flowers — but not in the
center.
Everyone
who wants to seriously examine plants needs a hand lens
to examine the surface features of a plant. The typical
one has 10x power. Swink & Wilhelm contains a diagram
illustrating over two dozen different terms. What does "hirtellous"
look like? Rich points to the stubble on my unshaven face.
It’s all as plain as the hair on my face? Yes —
as long as you have a copy of Swink & Wilhelm and the
help of fellow stewards.
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