Spring.wmf (18300 bytes) Plant Physiology (Biology 327)  - Dr. Stephen G. Saupe;  College of St. Benedict/ St. John's University;  Biology Department; Collegeville, MN  56321; (320) 363 - 2782; (320) 363 - 3202, fax;    ssaupe@csbsju.edu

Introduction to Time Lapse Movies:  Documenting Awn Movement in Stipa sp.

Objectives:  Upon completion of this laboratory you should be able to:

  1. to learn to use the QuickCam Pro digital video camera

  2. create and analyze a time lapse movie using ImageJ

  3. learn about awn movements in grasses

 Overview & Introduction:
            During this lab we will study awn movement in a native prairie species, porcupine grass (Stipa sp.).  An awn is an extension of a modified leaf that surrounds a grass flower.  The awns twist in response to humidity.  As an aside, this response was the basis for hygrometers manufactured in England in the 18th century.  We will study the movement of awns by making a time-lapse movie with an inexpensive digital video camera (Logitech QuickCam Pro).  Although the images produced by these cameras are not "Discovery Channel" quality, they are certainly adequate for many scientific investigations.  For more information about making time lapse movies and to see the potential of these cameras and others, visit the excellent "Plants in Motion" web site by Dr. Roger Hangarten, Indiana University.   



    To study awn movement we will set up a filming chamber.  Each group will be required to film and analyze data from at least one set of awns under our experimental conditions (warm vs. cold).  These data will be pooled for our final report.  In lab, I will show you how to actually set up the camera and analyze your video using ImageJ

PreLab Assignment

  1. Print and bring a copy of this document to lab. 

  2. Be prepared in class to answer the following questions (the articles listed in the references are available in the public folder and may be helpful):

  • What is an awn?

  • Do all plant species have awns? 

  • Where are awns found?

  • What is the possible function(s) of an awn?

  • Define hygroscopic.

  • How do you predict awns will respond to temperature?

  • Is awn movement a physical or biological process?

Question:  Is awn movement of porcupine grass affected by temperature?

Hypothesis:  Temperature will have a direct impact on awn movement.  Awns will twist at a faster rate in warmer temperatures than cooler temperatures.



  1. Set up the humid chamber.  Obtain water that was maintained at room temperature. Be sure to measure the temperature of the water.   Place a seed in the clay in the chamber, wet the filter paper, put a tiny colored pompom on the tip of the awn, and seal the chamber.  Position the camera system and begin to make the movie using the QuickCam software (Using a Quick Cam Pro Digital Video Camera)

  2. The finished movie will be an .avi file.  It is similar to an old-fashioned flipbook with a series of stacked images.  To analyze this movie we need to deconstruct the movie into its individual images.  I will show you how to do this using PaintShop Pro or QuickTime Pro. 

  3. We will analyze the individuals images using Analyzing a Movie Using ImageJ, a freeware program from the NIH.  It is equivalent to NIH Image (for Mac) or Scion Image.  We will use image J to measure the angle of rotation.  Note that you may need to manipulate your data some as the awn rotates through 360 degrees.

  4. Graph the angle of rotation vs. time.  Then calculate the rate of rotation (slope = regression). 

  5. Repeat steps 1-4 for the cold and warm treatments.

  6. Plot a summary graph showing the rate of rotation vs. temperature.

PostLab Assignment
:   At the conclusion of the experiment

  1. Write a brief abstract of this experiment.

  2. Append to your abstract:

  • raw data that you collected from your video analysis for all three temperatures

  • graph of the raw data - plot of angle of rotation vs. time - for each of the three temperatures.  Include a regression analysis of your data

  • summary graph plotting rate of rotation vs. temperature


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Last updated:  01/07/2009     � Copyright  by SG Saupe