Modified by James Deaver from Grasslands And Tundra Planet Earth Series Time-Life Books Inc., 1985
West Point Public High School
West Point, NE
Type of entry:
Type of activity:
Hands-on, simulation, and review / reinforcement.
Life Science, Biology, and Environmental Studies.
This activity helps students to understand the structure of a typical and
generalized grass plant. Students will be able to visualize the small spikelet
structures, such as glumes, lemmas, and awns that are so important in
grass identification. The model described here is a generalized grass plant that
closely resembles Big Blue Stem grass, Andropogon gerardi. Class time needed
for construction of the Grass Plant Model varies from 45 to 60 minutes.
Abstract of Activity:
Students will construct a paper model of a typical grass plant. This will include
an enlarged version of a single spikelet. Students will learn the names and structural
relationships of the parts of a generalized grass plant.
Lesson / Activity:
Materials needed for each grass plant model to be constructed include :
- 2 or 3 full sheets of recycled newspaper
- 1 copy of cut-outs Figures 1, 2, and 3, on colored paper if possible
- transparent tape, about 10 -12 inches
- pair of scissors
- one small paper clip
Procedure for construction of each model is as follows :
Making the culm or stem of the grass plant. Make a single, hollow tube by rolling up 2 or 3 full sheets of recycled newspaper. The tube should be about 22 or 23 inches long. At one end of the tube (to be top¹), secure outside edges with a small piece of transparent tape. About 4 or 5 inches from the other end of the tube (to be bottom¹), secure outside with piece of tape.
Making the roots. Cut longitudinal strips of about 4 inches in length at the bottom end of the tube. Cut many thin strips by going around the tube. Flare out this strips in all different directions.
Cut-out the single inflorescence and the three ligules from Figure 1. Learn the names of the parts to be cut-out. Write the names on the parts if you wish.
Slightly curl the inflorescence lengthwise and slide the long narrow section into the top of the hollow stem or culm. V-shaped cuts can be made between some of the spikelets of the inflorescence for a more realistic appearance.
Cut-out the three leaves from Figure 2. The outside¹ of each leaf is marked with dark lines representing the parallel veins. The inside¹ of each leaf is lacking these lines.
Secure a ligule to the inside of each leaf with a piece of tape. The ligule is placed so its serrated edge is visible above the auricle of the leaf. The ligule will be between the culm and auricle when a leaf is attached to the stem.
Attaching the Leaves to the culm. Begin at the top of the culm. A leaf is attached by curling its sheath, including auricle and node, around the culm, with dark veins to the outside, then securing with a piece of tape at the overlapping auricles and at the node end of the leaf. After the sheath is secure, bend the blade part of the leaf away from the culm.
Attach the next lower leaf so that its auricle is just below the leaf above. The ligule of the lower leaf may even overlap the node of the leaf above.
Position the lower leaf so that its blade is opposite of the leaf above. Grasses do have opposite leaf arrangement.
Attach the third and lowest leaf next. Its node should be just about where the roots begin.
Cut-out the many Spikelet parts from Figure 3.
Notice that most Spikelet parts have one or two dots near their base. Poke a small hole thru these dots using the end of the paper clip. As all the Spikelet parts are assembled, these holes should line-up, providing a point of attachment with one paper clip wire linked thru all holes.
Assembly of the Spikelet beginning with the most inside parts and working outward. Cut a slit along the dotted line near the base of the Ovary. Slide the long narrow section below the Grain thru the slit. Secure the Grain with a small piece of tape below the slit.
Fold the Palea lengthwise with the parallel lines on the outside. Wrap the base of the Palea around the Rachilla. Try to keep the holes lined-up.
Fold the Upper Lemma lengthwise. Wrap the base of the Upper Lemma around the base of the Palea but on the opposite side. The Spikelet parts have an opposite arrangement also. Notice the long Awn coming off the Upper Lemma.
Fold the Lower Lemma lengthwise. Wrap the base of the Lower Lemma around the base of the Upper Lemma but on the opposite side. Try to keep the holes lined-up.
Fold each of the Glumes lengthwise with the parallel lines on the outside. Wrap the base of one Glume around the base of the Lower Lemma but on the opposite side. Wrap the base of the other Glume around next, but on the opposite side. All Spikelet parts should now be aligned with the holes near the base.
Slide the end of the Paper Clip wire thru the holes until the clip acts as a secure hook thru all Spikelet parts. The Spikelet parts should be movable so as to simulate how Spikelets open up when grasses are mature and allow for the release of the the seed Grain. The assembled Spikelet can be hooked to the top of the hollow culm for storage with the grass model.
Evaluation / Assessment of student learning can be done by having students demonstrate and name each part of their completed Grass Model. The parts on one or more models can be numbered and these models used for test questions.
Extension / Reinforcement of the Grass Model activity might include:
Give the students real specimens of Big Blue Stem grass, Andropogon gerardi, or Little Blue Stem grass, Andropogon scoparius, and have the the students find and identify all the parts of the grass including the spikelet parts.
Have students design and build a grass model that is accurate for a specific species of grass. Is the leaf blade constricted, twisted or tapered ? Is the ligule shape acute, obtuse, truncate or emarginate?