Plants of the Mount St. Helens Lahar: Identification Activity, Field Trip

Goal: To provide practice in use of the dichotomous keying process for plant identification (This lesson should be preceded by: Classification: A Life Skill and School Site Ecosystem Activity. It may be used as preparation for Field Trip Lesson: Lahar Ecosystem Study; or as a stand-alone field activity.)

Objectives: Students will demonstrate ability to

  1. Define and correctly use botanical terms required by a typical plant key

  2. Defend the logic used to key-out one plant repre-senting each basic leaf form

  3. Demonstrate familiarity with a variety of plants commonly found in the lahar area of Mount St. Helens National Volcanic Monument.
Key Concept: A precise and logical classification system is a prerequisite for field study of natural features and lifeforms, and an important element in the scientific method and mindset.

Summary: Students practice using a typical dichotomous key to identify a prescribed number of plants they encounter on a field trip to the lahar.

Content Area: Science (botany)

Materials Needed:

Handouts:

  1. Plants of the Mount St. Helens Lahar-Worksheet
  2. Plants of the Mount St. Helens Lahar-Key
  3. Plant Identification Guide
Supplement:

  1. Botanical Glossary
  2. Classification: A Life Skill
  3. School Site Ecosystem Activity
  4. If possible, follow with Lahar Ecosystem Activity.
  5. teacher-designed pre-fieldtrip vocabulary activities
  6. four or five plants collected prior to arrival at lahar field site

Evaluation: Any teacher-designed evaluation of student progress toward accuracy in plant identification.

Instructional Sequence:

  1. On the way to the lahar, stop at Yale Lake Information Station, and collect a few representative samples of the basic leaf types. These might include:

  2. Offer these samples to students as examples. If time permits, let them use their keys to identify them on their own. Note that picking certain plant specimens for educational purposes is permitted, provided they are not rare or protected; however, there will be no further removal of plant specimens on the field trip.

  3. Review the keying process and pertinent vocabulary. Establish number of plants students will be expected to identify on the lahar, and in what format they will report their findings. If related classroom activities (Classification: A Life Skill and School Site Ecosystem Activity) have been done prior to field trip, and student readiness permits, use Handout: Plants of MSH Lahar-Worksheet. You may choose to supply plant names (see Key) and have students draw the plants; assign students to supply names, only; or ask students to provide both plant names and drawings.

  4. Encourage students to pay particular attention to unfamiliar plants at the lahar, rather than those they know, in order to challenge their plant keying skills.



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