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 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. Male Female 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? 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!