Deadly Plant Invaders Game



After planning this game and conducting evaluation activities, the students will be able to state the following about non-native plants:

1. Non-native plants compete with native plants for food, water, shelter, and space.

2. Non-native plants are often aggressive and may quickly crowd out native populations once introduced.

3. Removal of non-native plants by hand pulling, introduction or natural predators or disease, and passing legislation to prohibit sale of some non-native plants are methods that can be used to control non-natives.

Students will learn about the impacts of non-native plants have on native species by attempting to gather adequate minerals, water and space through a highly active role-playing game.

One of the most serious threats to the natural communities of plants and animals today is the introduction of non-native plant species by humans. When a certain non-native or exotic plant species is allowed to invade a natural native plant population, the results can be devastating for the natives. Often natural diseases or predators are not brought with the plants to their new homes thus causing a great growth in population size. This can lead to a decrease in native plant and animal diversity in a region as these uncontrolled species increase in number. The non-native species often out-compete native in obtaining the essential requirements for growth.

This decrease in plant diversity affects many different food chain and may lead to a mono-culture of plants and animals where once there was variety. Loss of endemic or native plant species may mean loss of valuable genetic material which could someday provide valuable medicines or foods. Loss of diversity makes our world a little less interesting and less beautiful.

This game will introduce your students to the dilemma of the deadly plant invaders.

4 cones or other markers to mark edges of playing field.
3 different colored playing pieces (poker chips work well). The total number of pieces will vary with the size of the group. Provide one playing piece of each color per player so that each player is able to survive the first round.
1 arm band for each player (all the same color)
3 arm bands of a different color than those used above
3 soft balls (Nerf type)
Whistle to signal the end of each round


Before play begins, designate a playing area by placing cones at edges/corners of the playing field. (A 30 foot by 60 foot area works well for 20 students). Scatter playing chips throughout the area. Each color represents a different need for the plants.

Color 1 - space and appropriate shelter
Color 2 - mineral needed to make food
Color 3 - water

Be sure to provide enough chips so each player may collect one chip of each color during the first round.

Round 1
All players will be native plants that populate a specific area. Everyone will line up along edges of the playing field at the start of each round. At the sound of the whistle players will enter the field, collect one chip and return to the edge of the playing field. After they reach the sideline, they return to the playing field and collect another chip of a different color. Once again they go to the sideline and then return for a chip of the third color.

After all three colors have been collected by a player, he/she moves to the sideline to wait for the signal to end the round, all players should survive.

Evaluate: notice that the "habitat" had ample food, minerals, water, and space for everyone to survive.

Round 2
This round will be played the same but will now include non-native plant species. Two players will wear an arm band to represent a non-native plant species. The non-native species are more aggressive and will be allowed to collect two chips per trip into the playing field. The non-native species will also be allowed to return to the field as often as they are able, but must collect three different colors in order to survive. A native plant species will be considered a survivor if he/she has collected three chips of different colors as done in round 1.

Sound the whistle to end round 2. Identify the survivors.

Evaluate: compare population sizes and impact the non-native species had on the native species.

Round 3
Native plants that did not survive round 2 become non-native species for this round. Give each new non-native species an arm band. Continue play as in round 2. At the end of this round, most - if not all - of the natives should no longer be surviving.

Evaluate as in round 2.

Round 4
Choose three players to be population controls for the non-native species: "hand-pullers" to remove non-natives. Give each an arm band (different color than the non-native plants).

The population controls will join this round and begin removing non-native plants with a ball, which is gently tossed and aimed below the waist. After a non-native is hit, he/she returns the gathered chips to the playing area then moves to the sideline to remove the arm band. The player immediately returns to the game as a native plant species. Native species are NOT to be tagged by the population controllers. After all chips have been collected identify the survivors.

Evaluate the effect population controls have on the native and non-native populations.

Round 5, if needed
Introduce more population controls and repeat round 4.

What do non-native plants compete with the native plants for?

What can non-native plants do to populations of native plants? How?

What can be done to control non-native plants?

Would passing laws to prevent sale of non-native plants that may cause threats to an area if they escape be a good idea? Why?

Discuss the advantages and disadvantages of introducing natural but non-native predators and disease to an area to help eliminate the non-native plant species.

Discuss the effects herbicides may have on the bio-diversity of an area if used to eliminate non-native plants.


References and supporting materials
Bureau of Land Management Weed Team, What's Wrong With This Picture? poster.

Cornell University, Media Services, Restoring the Balance: Biological control of the Purple Loosestrife, videotape, 1996.

National Public Radio, September 10, 1995, All Things Considered, report on introduction of exotic species.

Wilson, Edward O., The Diversity of Life, Harvard University Press, 1992.

Contact your local extension office or conservation district.


Last updated: April 10, 2015

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