To understand the fundamental methods of plant identification and to become familiar with its applications in modern science.
"...as scientists are better able to assess the conservation status of the species that compose an ecosystem, the more they will understand the health of that ecosystem. It is time to accelerate taxonomy and scientific natural history, two of the most vital but neglected disciplines of biology." (Stuart et al., Science 328: 177 (2010).)
This is the first lesson in a two-part series on plant identification and classification. This lesson provides students with an opportunity to explore how plant structures can be used in plant identification, a process important in the taxonomy and natural history disciplines. Any group of organisms can be used to develop identification skills. However, in this lesson, grassland plants are the focus.
Grassland Plants: Plant Classification, provides students with an opportunity to explore how plant structures can be used to build phylogenetic trees, a skill important in the taxonomy and natural history disciplines.
Research involving ecosystems and interactions between the species that inhabit them has played an important role in their conservation. Determination of a species' conservation status plays an integral part in maintaining ecosystem biodiversity. Two important goals set by the Convention on Biological Diversity are to: (1) decrease degradation of habitats and (2) address the decline of species. (Stokstad, Science 329:1272 (2010).) In order to catalog the world's plants, assess the conservation status of a species, and characterize natural habitats, it is necessary to have strong species identification skills. Taxonomy, broadly defined, is the scientific discipline which involves naming, describing, and classifying species. Since the focus of this lesson is on plant identification, you will use plant characteristics (structures) to come up with the common and/or scientific name for an unknown plant.
Animals and plants have a great variety of body plans, with different overall structures and arrangements of internal parts to perform the basic operations of making or finding food, deriving energy and materials from it, synthesizing new materials, and reproducing. When scientists identify and classify organisms, they consider details of anatomy to be more relevant than behavior or general appearance. (Science for All Americans, p. 60.)
After eighth grade, students should have a basic understanding of the Diversity of Life strand:
- 5A The Living Environment: Diversity of Life (6-8) #3
Similarities among organisms are found in internal anatomical features, which can be used to infer the degree of relatedness among organisms. In classifying organisms, biologists consider details of internal and external structures to be more important than behavior or general appearance. (Benchmarks for Science Literacy, p. 104.)
Internal and external structures are equally important in species identification; and as a skill, should be learned prior to studies of classification and relatedness among organisms. Students often have misconceptions about species identification. Therefore, it is important for you to query your students to discover these misconceptions.
Note: As a precautionary measure and to minimize risk, you should make yourself aware of any students who may have allergies to bee stings. Bees are found in the grasslands and pollinate flowers; the risk for a student to be stung is something to consider.
You can use the following resources for background information on plant identification:
- Stuart S.N., Wilson E.O., McNeely J.A., Mittermeier R.A., Rodríguez J.P. "The barometer of life." Science 328: 177. (2010)
- Stokstad, E. "Despite Progress, Biodiversity Declines." Science 329:1272. (2010)
Since an understanding of species identification is essential in biology, plant identification—determining a plant's name—is an important skill to develop in budding biology students. You should begin with a brainstorming session to assess what your students know about this topic and identify any misconceptions they might have about organismal identification. You can easily begin the brainstorming session by directly asking your students what they know about plant names. Start by bringing a couple of plants or plant parts to class that students would commonly eat (e.g., apples, celery, peaches) and some local "wild" plants they would normally see (e.g., trees, weeds). Focus on leaf, flower, and fruits in the order in which they are presented in the field guide you will use with your class. You can either perform this activity in the field or in the classroom. Use them with the following prompts to get the lesson started and write out students' answers in a field notebook (in the field) or on a chart (in the classroom):
- What is the name of this structure?
- (Answers will vary depending on the plants you use.)
- What is the name of the organism from which it was collected?
- (Answers will vary. See if students can provide a name for the plant—probably a common name.)
- This is a common name for this organism. What is the scientific name for this organism?
- (Answers will vary with the type of plant used.)
Next, have your students look at a variety of plant structures and their arrangement outside in the field (preferably) or provided in the lab. The best order of observing structures are usually from the least to most complex. Therefore, consider starting with organs (roots, stems, leaves), then flowers; then inflorescences (clusters of flowers); then fruits (the products of flower parts). This is your chance to connect structural terms (vocabulary) with living examples. The Botanical Society of America's Apple Poster provides an excellent resource to model the timed sequence of leaves and flowers emerging from a bud through fruit maturation. The observation of these structures will hopefully spark interest in your students to further explore how plants are constructed, grow, and develop. Understanding basic plant structure is fundamental to plant identification.
Students should begin by using their Plant Identification student esheet to view the Plant Identification and Classification video. In this video, your students will gain an understanding of the processes of plant identification and why the discipline is important in scientific research. After viewing the video, students should answer the questions found on the esheet (they can write their answers on the Plant Identification student sheet). Then discuss the introductory paragraph, the video, and student responses as a class.
- What structures can be observed to identify a plant?
- (Fruits, flowers, leaves, stems, and roots can be observed.)
- From which of these structures can a plant be most easily identified?
- (A plant can be most easily identified from its fruits and flowers.)
- What are the three types of leaf arrangement?
- (They are alternate, opposite, and whorled leaf arrangement.)
- What useful resources and equipment can be used to help you more accurately identify a plant (e.g., books, tools, etc.)?
- (Some useful resources are a hand lens, ruler, regional field guide, technical keys, etc.)
Next, your students will have the opportunity to practice identifying local plants. Before bringing your students out to the field to complete this activity, you should explore the school grounds or surrounding area and find a location where biodiversity is high and students can sample 10-15 plant species. Use the field guide that you provide to your students to identify several of the plant species in your study area. Students should follow the steps explained in the video when identifying their specimens and record data in the table provided on the student sheet.
Before students begin the activity, you should ask them questions about how to set up the activity. Suggested questions include:
- What structures should you observe to begin the identification process?
- (Answers may vary but lead students to understand that they should look at the leaves, fruits, and flowers of a plant.)
- What resources would be useful to help us determine what structures we are observing?
- (A field guide such as Peterson's Field Guide would be helpful for determining plant structures.)
- Why is identification important?
- (Answers may vary.)
- Once a specimen is properly identified, what can we determine using its scientific name?
- (The scientific name of a plant can help us determine its genus and species.)
Now students should do the activity as it is laid out on the Identification of Plants student sheet. One potential way that students could do the activity is for them to use a field guide of choice to identify several specimens. They should try to focus on structures that were important for proper identification. Then, they should sketch each specimen or collect a sample and press to preserve it. They could consider taking specimen photos if a camera is available. Finally, they should find the common and scientific names of specimens. You can follow the assignment and see a sample plant identification table on the Plant Identification teacher sheet.
This lesson provides an opportunity for students to complete a Plant Identification Table (see the student sheet). The identification table can be graded separately or included in a lab report about identification. Focus your assessment on information about their observations in terms of what structures were most important to observe for identification, how closely did their identification match that of their classmates, and how these skills might be applied in scientific research.
Another valuable form of assessment would be to have your students create their own field guides, using their gathered data, drawings, or photos, and both the common and scientific names of plants. Students should be creative in the process of designing their field guides, but should make them functional and use a scientific format. This activity can be assessed by having fellow classmates use the constructed field guides to try and identify the specimens addressed.
You can extend the ideas in this lesson by leading students through these Science NetLinks lessons:
- Identification and Classification of Grassland Plants (6-8)
- Grassland Plants: Plant Classification (9-12)
Grocery store botany: You can have students look at a variety of commonly eaten fruits, vegetables, and other plants/plant products they might find in the local grocery store. Use the questions in the Motivation section as prompts for a discussion. Students should know the common names of many plants they eat but they probably do not know the scientific names of the organisms from which their foods are harvested.
Compare the identification process using a field guide to the identification process using a technical key. This will familiarize them with more scientific terms and the processes scientists use in field work to identify a plant specimen. If you do not have access to a technical key in your school, contact a local university or herbarium for these resources.
Species Concepts: What constitutes a species? There is not one set definition for a "species." In fact, plant taxonomists usually recognize taxonomic species as opposed to biological species. The species concept would make for an interesting class topic, especially one which leads to a discussion of biodiversity.