Download Invasive Plant Species Scavenger Hunt

Lesson Plan Title: Invasive Plant Species
Grade Level: 5-8
Concept / Topic To Teach: Effects of invasive plants on the ecosystem
Specific Objectives:
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Students will identify invasive plant species in a given boundary
Students will discuss the effects of invasive plant species on the land and water
Students will explain how invasive plant species spread
Students will use a GPS device to mark waypoints for where invasive plants were
located
Required Materials: Scavenger hunt check list, laminated invasive species
identification and information cards, pencils, clipboards
Anticipatory Set (Lead-In): Students will need background knowledge on invasive
plant species. Go over the following information before beginning lesson.
Background:
For most people, weeds are just a minor nuisance in their gardens and lawns. However,
exotic or invasive weeds are more than a minor problem. Already infesting 70 million
acres in the United States (about the size of Nevada), invasive weeds continue to expand
their range by 4,600 acres a day - on public lands alone! Why is this a problem?
Exotic weed species are those that originate in other countries. Many exotic weed species
exist in North America. The natural checks and balances that keep these species under
control in the environment in which they evolved are not present in our country. Once
they have been introduced, exotic species out-compete native plants by stealing the
moisture, nutrients, and sunlight that native plants use. Areas in which the soil and plant
communities have been disturbed are the most vulnerable to invasion by exotic species.
From an ecological viewpoint, invasive weeds are a pioneer species. Natural plant
communities are altered when native species are eliminated. These alterations are often a
detriment to many other organisms, including humans. These invasive weeds are
responsible for threatening 2/3 of endangered species. In addition, they make land more
susceptible to wild fires. Weeds are a costly problem for rangelands and crops.
Most invasive species are native plants of Europe or Asia. Some of these invasive species
were introduced to North America by accident or unintentionally; some were introduced
intentionally. Some unintentionally introduced species entered the continent as seeds
hidden in bags of wheat or other grains. Other seeds were hidden in the hay or grass used
to feed animals during the long ocean voyage to this country. Some arrived as hitchhikers
in the fur of domestic animals that settlers brought to the New World. Others arrived as
hitchhikers in the clothing and bedding of the settlers themselves. Seeds were often hidden
in the soil used for the ship’s ballast. Examples of species that were accidentally
introduced include spotted knapweed and leafy spurge. Spotted knapweed probably
entered our country in the late 1800s, hidden in alfalfa seed from Eastern Europe. Leafy
spurge probably entered America in the early 1800s in Massachusetts. Species that were
intentionally introduced include horticultural and food plants. Three extremely invasive
horticultural species are Melaleuca, Eucalyptus, and Cytisus (scotch broom).
Weeds can travel in as many different ways as people can, and then some, since seeds are
small. Weeds can spread their seeds by wind, water, wildlife, livestock, machinery,
automobiles, boats, and people.
Why invasive species succeed
Invasive species possess highly effective adaptations that enable them to out-compete
native plants after they have been introduced into an area, especially in disturbed areas or
environments. Manmade disturbances include building roads, homes, shopping centers,
schools, and playgrounds. Farming, gardening, and landscaping can also disturb plant and
soil communities. Natural disturbances include eroded stream banks, volcanic deposits,
flood plains, and burned areas. Some invasive weeds have developed characteristics that
give them an advantage over native plants. These characteristics enable weeds to outcompete native plants. All weeds have not developed all characteristics; however, all weeds
are opportunistic, and weeds have a broad tolerance to a wide range of climate and soil
conditions.
Reproductive advantages
The seeds of many weed species can germinate in a variety of environments. Weeds often
grow and produce seeds rapidly, and weeds continue to produce seeds as long as the
growing season permits. Consequently, weeds produce a large number of seeds. For
example, a single purple loosestrife plant might produce millions of seeds in a single
summer. Seeds from invasive plants can often survive for many years, have a high rate of
germination, have high seedling survival rates, and possess highly effective adaptations for
dispersal. Russian thistle is an example of one weed that has developed effective
adaptations for dispersal. This weed has brittle stems and a round shape. These
characteristics help scatter the Russian thistle’s seeds as it tumbles. Many weeds have the
ability to self-fertilize and cross-fertilize. Many unspecialized visitors or the wind often
pollinate weed flowers. Many weeds are annuals that complete their life cycles quickly.
Some weeds can readily propagate without producing seeds. Perennial weed species, such
as Canada thistle, are often capable of vigorous vegetative reproduction. Canada thistle
can regenerate from a root piece less than one-half inch long. Vegetative reproductive
structures often survive through the winter.
Other Advantages
Some weed species have extra long roots, which enable them to easily access water and
minerals. The root of a leafy spurge plant can exceed 17 feet. It is difficult to remove longrooted weeds by pulling or digging. Creeping vegetative structures, such as roots and
stems, enable the weed to spread to new sources of water and nutrients. Buds on
reproductive structures, such as root nodes on Russian knapweed, can produce a new
plant. Some weeds, such as witchweed, dodder, and mistletoe, are parasitic. Parasitic
plants derive nutrients directly from host plants at the expense of the host plant. Some
weeds inhibit the growth of their competitors by exuding chemicals that poison the soil.
These chemicals prevent the normal growth of other plants. This phenomenon is known as
allelopathy. Examples of plants that limit crops through allelopathy include quackgrass,
giant foxtail, large crabgrass, johnsongrass, and common sunflower.
Step-By-Step Procedures:
Invasive Species Game:
1. Explain to students that Wyoming and this site in particular, has invasive species
present that could cause future problems if not kept in check or eliminated. Play the
following game to help students visualize the effects of invasive plant species on the
land.
2. Designate a playing area by placing cones at edges/corners of the playing field. (30' x
60' area works well for 20 students.)
3. Scatter playing chips throughout the area (each different colored chip represents a
different need for a plant or animal to survive. (White = Shelter/Space, Red =
Food/Minerals, Blue = Water)
4. Be sure to provide enough chips so each player may collect one chip of each color
during the first round in order to survive.
5. Round One: All players will be native to the specific area. Everyone will line up along
the edges of the playing field at the start of each round. At the sound of the whistle,
players will enter the playing field, collect one of the three different colored chips
and return to the edge of the playing field. After all of the students have returned to
the sideline, they return to the playing field and collect another chip of a different
color. Once again, they go to the sideline, returning a third time for the third colored
chip.
6. After a player has collected all three colored chips, he or she moves to the sidelines
to wait for the signal to end the round. All players should survive the first round.
7. Round Two: This round will be played the same as Round One, but will now include
non-native species. Two players wearing colored armbands represent a non-native
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 will also be allowed to return
to the playing field as often as they are able but must collect three different colors in
order to survive. The native species will be considered a survivor if he or she collects
three different colored chips as they had done in Round One.
8. Sound the whistle to end Round 2. Identify the survivors. Evaluate by comparing
population size and impact the non-native had on the natives.
9. Round Three: Native species that did not survive Round Two become non-native for
this round. Give each new non-native an armband. Continue to play Round Three
just like Round Two.
10. At the end of Round Three, most, if not all, of the native population should not
survive. Evaluate as in Round Two.
11. After Round Three, discuss with your students what they observed as they were
playing the game. As a class, have them begin to figure out how and why those
students who played as the initial non-native species were not only able to survive,
but to actually take over the entire playing field.
Scavenger Hunt:
1. Explain to students that using invasive species identification cards and GPS systems,
they will be going on a scavenger hunt to see how many Wyoming invasive species
they can locate in a given boundary of land (this will be dependent on age of
students and teacher preference). Boundary should include area bordering the
Tongue River.
2. Divide students into groups of three or four. Each group should have a set of
laminated identification cards, a GPS device (provided by the school), a scavenger
hunt check list, and a pencil.
3. Groups will set out to try to find as many invasive species as they can. When they
find a species, they should read the information on the back of the identification
card. Then, they should use the GPS device to get a waypoint for where they located
the species and record this waypoint on the scavenger hunt check list. Groups
should be aware that they might not find all the invasive species on the checklist.
4. Reconvene as a class and discuss which invasive species the groups found and where
they were located. For an extension, have students map these waypoints and discuss
patterns they see.
Closure (Reflect Anticipatory Set):
Have students answer and discuss the following questions.
1. Which invasive plant species did you find in the boundary? Were some species more
prominent than others?
2. Which invasive plant species did you find along the river? How does this affect soil
and water quality?
3. How do these invasive plant species spread?
4. What effects do invasive plant species have in your community?
5. How can you help control the spread of invasive plant species?
Assessment Based On Objectives: Scavenger hunt check-list and closure discussion
questions.
Locate as many of the following invasive plant species as you can. Use your
GPS to record the waypoint of each species that you find.
Plant Species
Black Henbane
Bull Thistle
Canada Thistle
Cheatgrass
Dalmatian Toadflax
Dyer’s Wood
Houndstongue
Leafy Spurge
Muck Thistle
Russian Olive
Salt Cedar
Spotted Knapweed
Whitetop (Hoary Cress)
Waypoint
Black Henbane
Interesting Facts
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Has been used as a medicinal plant since the Middle Ages
Been used as a beer flavoring many years ago
All parts of the plant are poisonous to animals and humans
Has a foul odor and has been called “stinking nightshade”
Description
Black Henbane (Hyoscyamus niger) is covered with greasy hairs and has a thick, fleshy taproot.
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Stems are upright, tough – almost woody - and can be very thick. Plants can grow to 1m or taller and may be
branched or unbranched.
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Leaves are alternate, large – up to 15 cm wide and 20 cm or more long – and have a heavy, foul scent. Leaf
edges are shallowly lobed (variable) and veins are conspicuous.
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Flowers are pale yellow with deep purple veins and throats and are borne on spikes. Flowers are
hermaphroditic – both male and female organs – and have a strong, unpleasant smell. The flower base forms
a 2.5 cm urn-shaped fruit with a thickened lid that pops off at maturity and spills the numerous, tiny, blackbrown seeds is primarily by seed production and sprouting from lateral roots to a lesser extent.
Habitat
Black henbane grows in a wide range of soil textures and pH but does require well drained soil. It does not tolerate
shade.
Bull Thistle
Interesting Facts
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Can grow up to 7 feet tall
Dense infestations of this spiny plant can exclude livestock and wildlife movement
Seeds have a silky down covering allowing windblown dispersal of great distances
Description
Bull thistle is a large spiny forb that can grow 7 feet in height
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Stems have spiny wings and grow 1 to 7 feet tall, with many spreading branches, and sometimes a single
stem
Leaves are more or less lance-shaped and 3 to 12 inches long, prickly hairy on the top and very hairy
underneath
Flowers Bull thistle flower heads are 1.5 to 2 inches in diameter, 1 to 2 inches long, usually solitary, and
more or less clustered at the ends of shoots and branches.
Seeds are 5 mm long, with a downy pappus
Habitat
Bull thistle is a very widespread weed that can grow in a wide range of environments but is most troublesome in
disturbed areas such as pastures, overgrazed rangelands, recently burned forests and forest clearcuts, and along
roads, ditches, and fences. Bull thistle is found on dry and wet soils, but is most common on soils with intermediate
moisture.
Canada Thistle
Interesting Facts
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Contrary to the name, Canada thistle did not come into the U.S. from our northern neighbor, but rather was
introduced in the 17th century from the Mediterranean region and southeast Europe.
Tea made from Canada thistle leaves has been used as a diuretic as well as for treatment of tuberculosis
It is the only thistle with male and female flowers on separate plants
Roots can branch out to 15 ft. wide and deep.
Seeds are winged and are easily dispersed by wind
New plants can develop from small broken pieces of the plant
Disperses a chemical that may inhibit growth of other plants
Seed may remain viable in soil up to 20 years
Description
Canada thistle is an herbaceous perennial in the aster family with erect stems, prickly leaves, and an extensive
creeping rootstock.
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Stems are branched, often slightly hairy, and ridged
Leaves are lance-shaped, irregularly lobed with spiny, toothed margins and are borne singly and alternately
along the stem
Flowers are rose-purple, lavender, or sometimes white flower and occur in rounded, umbrella-shaped
clusters
Seeds are tan curved and has a papery covering
Habitat
Canada thistle is found in open areas with a moderate amount of moisture but does poorly on wet soils lacking
sufficient oxygen. It can grow on many different soil types but it does not grow well in shade and is rarely found
within wooded sites, except in clearings. It is commonly found in abandoned fields or lots, abandoned gravel pits,
pastures, right-of-ways, roadsides, railway embankments, lawns, gardens, and agricultural fields. It also invades wet
areas with fluctuating water levels such as stream banks or irrigation ditches and sloughs.
Cheatgrass
Interesting Facts
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Cheatgrass (downy brome) is a noxious weed that can invade grassland communities and displace native
plants; it thrives in disturbed areas.
This weed can produce more than 10,000 plants per square yard and is highly flammable.
Cheatgrass can be controlled mechanically, biologically, chemically, or by applying fire under controlled
conditions.
Description
Cheatgrass is an annual—it lives for only one year/growing season and then dies. It reproduces by seed and is termed
a winter annual because its seed germinates from fall into winter. The plant reaches maturity in the spring and turns
brown and dies with the onset of summer.
The height of cheatgrass ranges from three to 30 inches. It has a crooked seed head and small soft hairs covering the
entire body of the plant. Leaves emerge dark green with a hint of purple. As it matures and begins to cure, cheatgrass
turns yellow to reddish-brown in color with seed heads ranging from two to six inches long at maturity. These seeds
have wedged awns that may be dispersed by wind and water, but most often they are spread by adhering to clothes
or to the coat of a wild or domestic animal.
Habitat
Cheatgrass often occurs as a significant component of foothills rangeland vegetation along the eastern front of the
Rocky Mountains. While cheatgrass is usually found along roadsides and disturbed sites in the east, it is highly
abundant in the west and has invaded disturbed and undisturbed grassland communities to become the dominant
species in many lower-elevation areas.
Dalmatian Toadflax
Interesting Facts
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One plant can produce 500,000 seeds in one year
Extensive root system - outcompetes other plants for nutrients and water
Contains toxic chemicals that can cause liver damage in grazing animals
Description
Dalmatian toadflax (Linaria dalmatica) is a short-lived, herbaceous perennial in the figwort family (Scrophulariaceae)
that grows up to 4 feet tall. Stems are somewhat woody at the base, and frequently branched in the upper portion.
Both leaves and stems are waxy. Leaves are heart-shaped, 1 to 3 inches long and with clasping bases. Flowers are
bright yellow with orange markings and elongate spurs and occur in simple racemes on the stems. Flowering occurs
from mid-summer to early fall. Seed capsules are ½-inch long pods and bear an average of 140 to 250 small black to
brown seeds with wings. Taproots may reach depths of 4 to 10 feet, and lateral roots can extend 12 feet from the
parent plant.
Habitat
Dalmatian toadflax is typically found along disturbed sites, roadsides, clear cuts, railroad right-of-ways, fences,
croplands, pastures, and rangelands. It prefers dry sites with coarse, well-drained soils.
Dyer’s Wood
Interesting Facts
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It was introduced to the eastern United States in the 17th century as a source of indigo dye and as a
medicinal herb.
Plants can produce as many as 10,000 seeds per year.
Has a thick tap root that can exceed 5 feet in depth.
Description
A stout, erect winter annual, biennial, or short-lived perennial in the mustard family.
Stems Erect, somewhat woody, ranging in height up to 4 feet.
Leaves have a distinct cream-colored midrib and powdery white film on the upper leaf surface.
Flowers are small and yellow (3mm in width), located in dense, flat-topped racemes. Each flower has the four petals
in a cross-shape characteristic of the mustard family.
Seed/Fruit are purplish-brown, tear-drop shaped, winged and pendulous.
Habitat
Dyer’s Woad thrives in light sandy to gravelly soils and will even grow in rocky soil. Unlike other mustards, it does not
require disturbance to become established.
Houndstongue
Interesting Facts
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The plant’s name may have come from the shape and texture of the leaf resembling that of a dog’s tongue. Or
that the name came from the belief that a leaf worn in the shoe could ward off dog attacks.
Extracts of the roots and leaves of houndstongue have been used in folk remedies for various ailments
including fever, eczema, acne, and hemorrhoids.
An ointment derived from houndstongue is reported to cure baldness.
The red pigments of the outer root surface are anti-bacterial and may have wound healing abilities.
Roots and leaves have been used as pesticides and used to repel moles and other rodents for stored foods.
The foliage is toxic to domestic and wildlife.
Houndstongue is dispersed primarily through seeds adhering to livestock and wildlife.
Description
A stout, erect perennial forb in the borage family.
Stems are upright, branched in the upper portion, and can grow to 30 inches tall.
Leaves are oblong with numerous soft white hairs on both surfaces. They have distinctive veins, smooth margins ,and
can be up to 12 inches long.
Flowers are reddish-purple, have 5 petals and hang in clusters.
Seed/Fruit are flat, teardrops shaped, and have a hard spiny husk with barbs. Protruding barbs adhere to fur or
fleece of wildlife, domestic animals, and human clothing.
Habitat
Prefers drier, well-drained sites, but is tolerable to alkaline soils. Houndstongue is often associated with disturbed
sites. It is also shade tolerant and can be commonly found under trees and shrubs where livestock and wildlife bed
down.
Muck Thistle
Interesting Facts
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A single flower head may produce 1,200 seeds and a single plant up to 120,000 seeds
Seed may remain viable in the soil for over ten years
Unpalatable to wildlife and livestock
Can grow to 6 feet
Description
Muck thistle is a non-native biennial forb that reproduces solely by seed.
Stems are upright, green-grayish, and can grow up to 6 feet tall with spiny wings.
Leaves are spiny, waxy, and dark green in color with a light green midrib/
Flowers are purple, large in size (1.5 to 3 inches in diameter), nodding, and terminal.
Seed/Fruit can produce thousands of straw-colored seeds adorned with plume-like bristles.
Habitat
Muck thistle grows from sea level to about 8,000 ft evlevation, in neutral to acidic soils. It invades open natural areas
such as meadows, prairies, and grassy balds. It spreads rapidly in areas subjected to frequent natural disturbance
events such as landslides.
Russian Olive
Interesting Facts
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Can convert atmospheric nitrogen to ammonia allowing establishment in poor soil conditions
Roots can grow as deep as 40 feet
The fruit floats and is easily transported and dispersed along waterways
Tolerates a wide range of environmental conditions including high winds, flooding, drought, extreme
temperatures, saline or alkaline soil conditions
Description
Russian-olive is a small deciduous tree or large thorny shrub that can grow 15 to 30 feet in height
Stems loosely arranged; reddish-brown with silvery scales; twigs are thorn tipped with silvery scales
Leaves are simple, alternate, 1-3 inches long, lance-shaped and silvery on both sides
Flowers are bell-shaped, single or clustered in the leaf axils, fragrant, yellowish on the inside and silver outside
Seed/Fruit are dupe-like, .5 inches long, light green to yellow with silvery scales, hard and fleshy
Habitat
It is found along fields, open areas, grasslands, stream banks, lakeshores, roadsides, and urban areas, sandy and
bare mineral soils. Seedlings are tolerant of shade and thrive in a variety of soil and moisture conditions, including
bare mineral substrates.
Salt Cedar
Interesting Facts
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Extremely high water consumption - mature plants can use 200 gallons of water per day!
Tolerates highly saline soil
Salt cedar plants cause surrounding soils to become highly saline, which eventually eliminates all native plants
Monocultures of salt cedar have a devastating impact to riparian habitats - causing a severe decline in wildlife
populations
Wildfires are more frequent in salt cedar stands
Difficult to control - new plants can be established from seed and live stems
Description
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The narrow leaves are small (1.5cm) and grayish green, often overlapping and crowding on the stems.
Although the leaves have the appearance of an evergreen, they are actually deciduous
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The deep pink to almost white flowers crowd in many slender spikes, forming dense masses at the top of the
branches. The flowers are about 1.5mm across, and have 5 petals. The seedpods are pinkish red to greenish
yellow, and will break into 3 to 5 parts when mature. A tuft of fine silky hairs adorns the tip of the tiny seeds
The saltcedar's bark is a reddish brown while the wood is soft and white. The smooth bark ridges and furrows with
age. Tamarix have a deep taproot and extensive lateral rhizomes, which profusely branch upon contact with water
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Habitat
Salt Cedar typically occupies sites with intermediate moisture, high water tables, and minimal erosion. Saltcedar
mainly occurs along floodplains, riverbanks, stream courses, salt flats, marshes, and irrigation ditches in arid regions.
Spotted Knapweed
Interesting Facts
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Grow extremely fast in the spring - snatching up much of the available nutrients and water
Creates thick infestations - reduces native vegetation by 90%
Plants release it own herbicide that inhibits the growth of surrounding vegetation
Poisonous to horses - causes chewing disease that had no cure
Large infestations significantly increase soil erosion
Description
Spotted Knapweed was introduced in 1893 from Europe into Victoria, BC. Since then it has spread across most of the
United States. Spotted Knapweed is a biennial plant that has purplish colored flowers. Its leaves are covered with
translucent dots. This is how the plant got its name. This plant spreads by seeds, not runners.
Habitat
Spotted Knapweed prefers open habitats with full sun. It can withstand harsh dry conditions and poor soil. Found in all
lower 48 states except Oklahoma, Texas, and Georgia.
Whitetop (Hoary Cress)
Interesting Facts
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Difficult to control due to an extensive and deep root system
Resistance to many chemicals
Capable of tainting meat and milk of grazing animals
Capable of poisoning livestock
Quickly establishes in disturbed areas
Description
A stout, erect perennial in the mustard family.
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Stems are upright, grayish, and can grow to 2 feet tall.
Leaves are blue-green to gray green that are alternate, covered with soft white hairs, and lance to arrowhead
shaped. Upper leaves clasp stem.
Flowers are numerous, white with four petals borne on ½ inch long stalk. Dense clusters create a white flattop appearance.
Seed/Fruit are heart shaped capsules with reddish brown seeds.
Habitat
It prefers soils with neutral to alkaline pH and disturbed sites, including excessively grazed areas. It can be found in a
variety of non-shaded habitats such as fields, meadows, pastures, open grasslands, waste areas, roadsides,
watercourses, along irrigation ditches, and at the edge of riparian habitats.
References
Bureau of Land Management. (2014). Some common invasive plants in Wyoming.
Retrieved from http://www.blm.gov/wy/st/en/programs/weeds_pests/species.html
National Teacher Training Institute. (n.d.). Battlefield Earth. Retrieved from
http://www.thirteen.org/edonline/ntti/resources/lessons/battle/b.html
Oregon Natural Resources Education Program. (n.d.). Invasives: plants on the move.
Retrieved from
http://weedinvasion.org/pdfs/Facts/where_do_they_come_from.pdf