Download Plant Science Lessons

Plant Science
Lessons
Unit 1, Lesson 4
Using Dichotomous
Keys to Classify Plants
Student Learning Objectives
As a result of this lesson, the student will …
 Objective #1: Define dichotomous key and
explain its usefulness
 Objective #2: Utilize dichotomous keys to
classify organisms
Dichotomous Keys
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Dichotomous means to divide
into two parts.
A dichotomous key is
comprised of sets of two
questions.
Once this question is
answered, it leads to another
set of questions.
Therefore a dichotomous key
is a device for identifying
organisms based on the
answers to a series of
questions, with each question
involving alternate choices.
Female
Male
Belt
No Belt
Jewelry
No Jewelry
Who might use dichotomous keys?
Scientists
 Many times scientists have to identify unknown plants. A
cattleman may send a small sample of a plant that he suspects
killed a cow to the laboratory. Dichotomous keys might make it
easier to identify these plants.
Turf Specialists
 Grasses are among the most difficult plants to identify,
especially the cultivated turf varieties. Identification of turf
grasses is essential to proper management of the grass.
Extension Specialists
 Farmers, gardeners or ranchers often bring in samples of
plants that need to be identified, many that are invasive to the
production practices of agriculturalists. A dichotomous key
might be used to assist in this identification practice.
Who else might use dichotomous
keys?
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YOU!!
Utilize dichotomous keys that are already
made to classify leaves and plants.
Make new dichotomous keys to assist you
in identifying crops and weeds!