Plant Science Lessons

1. Plant Science Lessons Unit 1, Lesson 4 Using Dichotomous Keys to Classify Plants

2. 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

3. Female Male No Belt Belt No Jewelry Jewelry Dichotomous Keys • 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.

4. 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.

5. Who else might use dichotomous keys? • 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!