18 – 1
Chapter 18
The Classification of Plants and Other Organisms
CHAPTER OUTLINE
Taxonomy
Species are classified using binomial nomenclature
The species is the basic unit of classification
Plants and People: Plant Exploration
CHAPTER OBJECTIVES
1. Define taxonomy and explain why the assignment of a scientific name to each species is
important for biologists.
LECTURE OUTLINE
I. Who was Carolus Linnaeus?
A. What is the system of naming plants first used by Linnaeus and still used today?
II. How are organisms classified into groups?
A. What is the basic unit of classification?
B. What are levels of classification below species?
C. How does a hierarchical system work?
III. What is the basis for modern classification?
A. What is systematics?
IV. How are the organisms of the world divided into six kingdoms?
A. How have kingdom-level groupings changed in the past 200 years or so?
KEY TERMS
binomial system of
nomenclature, p. 351
family, p. 354
genus, p. 354
phylogeny, p. 357
paraphyletic, p. 360
TEACHING TIPS
1. There are some good stories about Linnaeus. He had a magnificent garden at his estate
outside Uppsala, including a “clock garden” that was divided in sections with plants that
opened their flowers at different times of the day. By looking out of his window, he could
tell the time by seeing which flowers were opening and which were closing. He devised
2. Be sure to emphasize the distinction between the species name and the specific epithet.
3. A helpful mnemonic to remember the order of hierarchical classification categories is
“kings play chess on fine green sand.”
4. As a lab or discussion group exercise, give groups of two or three students the same
packets of 10–12 objects described in Chapter 1, Teaching Tip #6. This time, ask them to
write a dichotomous key that anyone who can read would be able to use to identify the