Fine-tip Forceps. Metric ruler. Scanner ( dpi) Gynecandrous Inflorescence Leaf sheaf Ligule Morphological Characters

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Vernon York
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1 Lesson 2: How to Measure Sedge Morphological Traits High School Biology Objectives: 1. Students will work with a collaborating plant systematist to learn the basics of sedge morphology, the overarching goals of the research project, and their role in the project. 2. Students will learn to utilize herbarium specimen sheets without damaging the specimens. 3. Students will learn to measure morphological characters particular to a group of species within the genus Carex (Family Cyperacae). 4. Students will familiarize themselves with the basic vocabulary needed to collect morphological data for the research project. Time Frame: 2-40 minute class periods Materials: Herbarium Specimen Sheet Dissecting Microscope Dissecting Probe Fine-tip Forceps Metric ruler Scanner ( dpi) Photoshop (or comparable photo-editing software) Computer Work Stations Key Vocabulary: Achene Androgynous Basal Cauline Culm Gynecandrous Inflorescence Leaf sheaf Ligule Morphological Characters Perigynium Pistillate Staminate Procedures: 1. Students will hear a presentation given by a plant systematist about the morphololgical data collection that will be involved in the research project. Presentation of key vocabulary and collection protocol will be the main focus of the presentation. 2. Students will have the opportunity to ask questions concerning vocabulary understanding and project parameters. 3. Students will be led through a guided practice session to learn the protocol required for collecting morphological character trait data in the next lesson. 4. All data will be recorded on the student worksheet for this first round of measurements to enable students to learn the protocol for measuring morphological characters. It will also provide an opportunity for the teacher to assess learning of the procedures.

5. It may be necessary to model use of the dissecting microscope and the tools required to make measurements. 6. Work through each step of the protocol with the students.

2 5. It may be necessary to model use of the dissecting microscope and the tools required to make measurements. 6. Work through each step of the protocol with the students. The first step involves measuring the width of Flowering Culms. Be certain that the students understand the vocabulary being used as well as the method for using tools (needle probe, metric ruler, and forceps). It is critical to remind the students to measure the culm, not the leaf sheath. In addition, it may be necessary to frequently remind the students that all measurements should be taken to the nearest tenth of a millimeter. Culm Leaf Sheaf (alabamaplants.com, 2012) 7. Work through the second measurement step involving measuring the two widest Leaf Blades. Be certain that students can find the widest cauline or basal leaves. It may be necessary to move the ruler up and down the blade to find the widest point. Remind the students to measure width to the nearest tenth of a millimeter. 8. Aid students in locating the Spikes in order to identify them as staminate, pistillate, or bisexual (androgynous/gynecandrous). They should count the number of spikes on each of 3 Culms/Inflorescences. Be aware that not every specimen students measure will have every type of spike.

Bisexual Spike (boblinks.com) (etc.usf.edu, 2012) 9. Aid students in locating the two longest culms of each spike type available. They should measure lengths to the nearest tenth of a millimeter. 10.

This requires delicate work under the dissecting microscope and use of the probe and forceps to gently release each perigynium from the spike.

Instruct students to place all of the released perigynia into a clear petri dish.

3 Bisexual Spike (boblinks.com) (etc.usf.edu, 2012) 9. Aid students in locating the two longest culms of each spike type available. They should measure lengths to the nearest tenth of a millimeter. 10. Instruct students to gently remove the spike included in the packet attached to the specimen sheet. Demonstrate how to carefully remove the perigynia from the spike. This requires delicate work under the dissecting microscope and use of the probe and forceps to gently release each perigynium from the spike. If you have a scope cam, demonstration of this step can be easily accomplished. Be aware that this can be a tedious step. Perigynium Pistillate scale Perigynium and scale (eol.org, 2012) 11. Instruct students to place all of the released perigynia into a clear petri dish. The petri dish should then be placed on a scanner and scanned into Photoshop at dpi in order to get a clear image. If possible, the students should save the scanned image labeled with the collection number of the specimen to a common folder accessible to the teacher. If internet access is available, Dropbox or Google Drive would be acceptable options. A flash drive could also be used if a shared drive is not available.

Number of perigynia released-use the paintbrush tool to mark each one that is counted. b. The total number of perigynia should be calculated with the formula: Total Perigynia Number of Spikes.

4 12. Guide the students in opening their scanned file image on a separate computer. In Photoshop the image should be cropped and increased in size so that each perigynia can be clearly viewed, counted, and measured. Students should record the following: a. Number of perigynia released-use the paintbrush tool to mark each one that is counted. b. The total number of perigynia should be calculated with the formula: Total Perigynia Number of Spikes. You will probably need to help students identify the original culm from which the spike came. c. The length of 3 of the largest perigynia (measure from base to the tips of the teeth)-use the measuring tool calibrated to the nearest tenth of a millimeter. d. The width of the 3 largest perigynia-may require taking a few measurements to find the widest point. Use the measuring tool calibrated to the nearest tenth of a millimeter. Measure to nearest tenth of a millimeter (sigesplants.jp, 2012) 13. Demonstrate for the students how to carefully release an achene (seed) from each of 3 perigynia. Once again, this requires working under the microscope with a probe. 14. Students should place the achene in the clear petri dish, scan into Photoshop at dpi, and measure the following: a. The length of each achene- this should be measured from the base of the achene to the point at which the style attaches to the achene apex (in some sedges this is not an abrupt transition, in which case use the point of inflection at which the curve from achene to style changes from convex to concave). b. The width of each achene (GramGloss.htm, 2012) Point of Inflection 15. Instruct students to return the spike, all perigynia, and the 3 achene to the original packet. Students should then return the specimen and the packet to the teacher.

5 Check For Understanding: It is very important to pay close attention to individual groups of students as they progress through this first set of measurements since the methodology and vocabulary are most likely unfamiliar. Encourage them to work carefully and to ask frequent questions if necessary. Assessment: 1. How might you expect your measurement of structures to relate to where and how sedges live? You will want to consider how they might gather resources to live, compete, and reproduce. Look for answers that reflect that the students are making correlations between such ideas as spike shape and number of seeds, number of spikes and the size of seeds, or the number of staminate and pistillate spikes in relation to seed size and number. The students should be able to support their ideas with evidence from their data collection. 2. Compare the specimen data you gathered with that of another group that was looking at a different species? What similarities and differences did you discover in the data? Look for answers that compare structure to function with evidence supplied to support main ideas. 3. In a detailed and well-constructed paragraph, discuss what you learned about sedges from exploring a single herbarium specimen. Answers will vary. Look for main ideas that are clearly supported by evidence from the data collections. In addition look for answers that show clear interpretations of the meaning of the evidence presented.

16B Flower Dissection

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