Made for Each Other
Students will identify the type of adaptations that flowers have developed to attract pollinators. Students will describe the beneficial relationship between pollinators and the flowers they pollinate.
Pollination, adaptations, interrelationships
Pa Environment and Ecology Standards Addressed
- 4.3.4. Environmental Health
C. Understand that the elements of natural systems are interdependent.
- 4.7.4. Threatened, Endangered and Extinct Species
A. Identify differences in living things.
B. Know that adaptations are important for survival.
Other Pennsylvania Standards Addressed
- Science and Technology
- Teaching Methods
- Observation, comparison, identification, role playing
Planning & Planting Tips
Include plants with different flower shapes, colors, and insect guides – see background section
Flower Types attachment, pollinator cards, flags of different colors (one per flower), pencils
While we find flowers beautiful, it is for the pollinators that the flowers go to all the trouble.
Most plants need to be pollinated to produce fruits and seeds. To understand pollination we must look at the parts of a flower.
The male flower parts are called stamens. The pollen-producing part of the stamen is called the anther, which is held aloft on a stalk called a filament. Each pollen grain is unique to its species. Pollination occurs when the ripe pollen grains are transported from the anthers to the female flower part, called the pistil. The pistil is made up of the stigma, style, and ovary. The stigma is sticky and is designed to trap pollen. Once pollen lands on the stigma, it sends a pollen tube down a stalk, called the style, which leads to the ovary at the base. There it enters an ovule and fertilization takes place. This is the beginning of a new seed. The ovary develops into the fruit that encloses the seed.
Some plants can pollinate their own flowers. This is called self-pollination. These plants transfer pollen from the stamen to the pistil of the same flower or to a separate flower on the same plant. Examples of self-pollinating plants are peas and wheat.
Most flowers have cross-pollination. This means that pollen is transferred from the stamen on one plant to the pistil on a different plant of the same species. Plants that use this type of pollination rely on pollinators, which can include wind, water, insects, birds, or mammals.
Wind is a pollinator for many types of plants including pines, oaks, and grasses. These plants usually have small, inconspicuous flowers that bloom in early spring before the leaves are fully developed. Water transfers pollen for some aquatic plants. The pollen is released on the water’s surface and floats to other flowers.
Scientists estimate that there are many thousands of animal pollinators. In North America, most of the pollinators are insects like bees, butterflies and beetles, or vertebrates like hummingbirds or bats. Animal pollinators and the flowers they visit have unique features that let them work together. Animals carry the pollen in different ways. Birds or bats carry pollen in their feathers, fur, or hair. Although insects lack hair, they have something just as good - bristles on their legs, head, and body. Honeybees have tiny bristle baskets on their legs for carrying pollen back to the hive.
Flowers come in a variety of sizes, shapes, colors, and perfumes to attract their particular animal pollinator. Most flowers produce nectar, a high energy food for many pollinators. Petals not only attract with their color, but may serve as a landing platform for a visiting insect. Some flowers have ingenious ways to make sure their visitor carries pollen away. When a bee lands on the lower petal of a snapdragon, its weight causes a stamen to swing down and dust the bee with pollen.
Color plays an important role in attracting the ideal pollinator. Hummingbirds often, but not always, are attracted to red flowers. Interestingly, red flowers are typically full of carbohydrate-rich nectar, which provides instant energy for these fast-moving birds. Bees, on the other hand, can’t see red and are attracted to blue, yellow, and violet flowers. The eyes of bees, butterflies, and flies are especially sensitive to color, which helps them find flowers.
Many flowers have a set of nectar guides that act as runways to show a pollinator how to enter the blossom and locate the nectar or pollen. Narrow stripes converging at the center of the flower are common markings. A cluster of dots or a checkered pattern on a particular petal show an insect the best place to land and which direction to go from there. Insects see differently than we do, because they are sensitive to ultraviolet (UV) light which is invisible to us. UV light makes the reproductive areas of some flowers stand out. To our eyes a buttercup appears solid yellow, but to a bee the flower’s center is darker because it reflects UV light.
Plant structure is also important in attracting specific pollinators. Queen Anne’s Lace has its nectar right at the base of its tiny flowers, so a pollinator with a short proboscis, such as honeybees or beetles, can reach it when they crawl on the flower. Bumblebees, butterflies, and moths have long proboscises, which allow them to reach less accessible nectar. The long curved shape of a columbine flower complements the long tongue of all of these pollinators. However, the downward tilting flower requires the pollinator to hover. Butterflies do not feed this way, but hummingbirds do which makes them an ideal pollinator of this plant.
Another type of lure is aroma. We can all appreciate the sweet scent of honeysuckle on a warm summer night. This is the time that the honeysuckle is visited by its pollinators, nocturnal moths who “smell” with their feathery antennae. Moths and bats rely heavily on scent to locate the flowers they visit, especially since they fly at night. Birds are not very sensitive to fragrance and rely more on visual cues.
Pollination is extremely important to people. Bees pollinate more flowers than any other creature on Earth, without which many plants would be unable to produce seeds or fruit. Without pollinators, we would not only have a world without flowers, but a world without many types of food. On a global scale, animals pollinate more than three-fourths of the staple crop plants people eat. Scientists estimate that one out of every three bites of food we eat is the result of pollination. Today, many pollinators are declining primarily due to loss of native plant habitat and the extensive use of pesticides.
When insecticides are used to kill pests, many pollinators and other beneficial insects are also killed. To help protect pollinators consider other options before using insecticides. Choose plants that are appropriate to your growing conditions. Plants placed in the wrong location won’t thrive and are more susceptible to problems. Identify the pest first, in order to select the best control method. Consider hand-picking, traps, or row covers. Look for the presence of beneficial insects that might help to control pests. If insecticide use is necessary, avoid spraying when pollinators are active. Honeybees are not active in late evening and early morning. Select a product that is least toxic to the environment and most specific to the insect pest you are trying to control. Insecticidal soap, for example, is an effective control for many pests, but is least disruptive to beneficial insect populations.
Pollinators and Their Preferred Flower Types
Some of the most important pollinators. Bees are not sensitive to red, but are attracted by yellow, blue, or lavender flowers. They are sensitive to ultraviolet light. Bee flowers are usually fragrant with open, tubular shapes and landing platforms. Flowers: Marsh Marigold, Foxglove, Gaillardia
Prefer flowers with long, tubular shapes arranged in a cluster and landing platforms. Butterflies like purple, yellow, orange, and white flowers. Flowers: Phlox, Milkweed, Butterfly Weed
Attracted to flowers that produce a lot of nectar and come in bright colors, especially red. Their long beaks are adapted for long, tubular flowers. They are good at hovering and can feed from flowers that hang upside-down. Hummingbird flowers often lack fragrance, since birds have a poor sense of smell. Flowers: Hibiscus, Trumpet Vine, Fuchsia, Cardinal Flower
These insects are mostly nocturnal and visit light-colored flowers that are open at night. Moth flowers are tubular in shape and often have very sweet fragrances. Flowers may lack landing platforms because moths can feed while hovering. Flowers: Nicotiana, Evening Primrose, Honeysuckle
Prefers tiny, light colored flowers with nectar. Flower: Small-flowered Orchid
Attracted to tiny, light-colored flowers with strong musky odors. Some fly pollinated flowers are a distinctive red-brown color and produce the scent of carrion or rotting meat. The flies go to the flower thinking that the “meat” is a good spot to lay their eggs and inadvertently pollinate it. Flowers: Skunk Cabbage, Red Trillium, Carrion Flower
Beetles are poor fliers and are attracted to flowers having large petals with lots of landing space. Beetles are pollen eaters and need flowers that provide extra pollen. Beetle flowers produce a fruity fragrance and have white or pastel colors that can be seen from a distance. Flowers: Beetle Magnolia, Poppy
Bats have long noses and tongues that allow them to reach nectar deep inside the flower. They prefer flowers that are light-colored, usually white, with strong fruity or musky scents. North American bat pollinators live in the southwest. Flowers: Agave, Organ Pipe Cactus
Flowers are usually small and inconspicuous with no scent. Often they bloom early in spring before leaves are out. The pollen is held so it is easily caught by the wind. Flowers: Grasses, Oaks, Ragweed
*While each pollinator has a flower type it prefers, it may visit many types of flowers.
- Prepare pollinator cards. Photocopy the Pollinator Cards attachment and cut apart.
- Select one flower in the garden for each pollinator to visit. Mark each flower with a flag, so students know which flowers they may choose. Each flower should have a flag of a different color.
- If necessary, write additional clues on a card and attach them to the flower. For example: “I have a lot of nectar.”
- To include flower types listed on the pollinator cards that are not growing in your garden, use a picture, plastic plant, or a potted plant with the appropriate characteristics.
Doing the Activity
In the classroom
- Ask students to tell you which type of flower is their favorite and why. Explain that students picked different types of flowers for different reasons – size, color, scent, etc. Tell students that different plant pollinators have flower favorites, too.
- Explain that to produce seeds, most plants must receive pollen from another plant of the same type or species. Some plants depend on the wind to carry their pollen grains, but others take advantage of insects, birds or mammals to carry their pollen.
- To attract a pollinator many plants present attractive flowers with sweet tasting nectar, but different pollinators are attracted to different things. They may visit certain types of flowers more often, because they prefer specific colors, flower shapes or fragrant scents. (If students need more preparation, use the background information and Flower Types attachment to review this concept.)
In the garden
- Break the students into groups. Tell them they are about to become pollinators in search of the perfect flower. Give each group a pollinator card and a pencil. Have them read the descriptions on the card carefully. Tell them that one of the flowers marked with a flag is a good match for each of the pollinators.
- Tell students that when you give the signal, they should crawl, buzz, or fly to the flowers and find the one that is best adapted to them. Only flowers marked with flags can be selected. When each group has found a flower, they should record the color of its flag on their pollinator card. Regroup and review each group’s selection. Ask each group to explain what type of pollinator they are and why the flower is a good match. Use the background information to discuss the features of various pollinators and the flower adaptations that would attract them. How do the flowers benefit from the insects? How do the insects benefit from the flowers?
- Group students together and observe other flowers in the garden. Discuss the shape, color, and scent of the flower. Have students look for nectar guides, such as stripes, dots, or patterns of color that would lead the insect to the nectar. Ask students what type of pollinators they think would visit the different flowers.
- Have students observe the garden to see if any pollinators visit.
- Discuss how people benefit from pollinators their role in our food supply. Ask students what might cause a decline in pollinator populations. Explain that loss of habitat and overuse of pesticides reduces populations. Tell students that when certain pesticides are used to control insect pests, they can also kill pollinators and other beneficial insects. Discuss possible alternatives for pest control that would be less harmful to pollinators.
- Correct matches of flowers and pollinators.
- Show students pictures of flowers and ask them to name the type of pollinator the flowers would attract.
- Ask students to list their favorite color, shape, scent, and food. Have students work in pairs. Instruct each student to share their list of favorites with their partner. Based on their partner’s list, have each student design a flower that would attract their partner if he/she were a pollinator.
- Have students observe a flower over time. Have them record the different types and behavior of the pollinators that visit it.
- Parrella, Deborah, Project Seasons, 1995
- Ida Cason Callaway Foundation, Pollination, Vol.16 No. 3, 1992
- Smithsonian Institute, Office of Education, Partners in Pollination
I am a honeybee. I can’t see red, but I love other bright colors like yellow, blue, and lavender. I like sweet fragrances and petals with stripes or patterns that guide me to the nectar. I like a landing platform, so I can crawl around to find the nectar. I have a short proboscis; so long flower tubes aren’t for me, unless I can crawl inside. I love to gather lots of pollen in the “baskets” on my legs.
I am a hummingbird. Red is my favorite color, but I also visit orange, pink, and yellow flowers. I can’t smell a thing, so don’t bother with perfume. I have quite a long tongue and like a long tube filled with nectar. Because my wings let me hover, I don’t need to land and can even feed from flowers that hang upside down!
I am the wind. I don’t care how a flower looks or smells. In fact most of the flowers I pollinate are quite small and not very noticeable. I like flowers with lots of tiny, lightweight pollen that I can blow around.
I am a male mosquito. When I gather nectar, I look for tiny light-colored flowers that are about the same size as me.
I am a butterfly. I love bright-colored flowers – especially yellow and orange. I need a landing platform or a cluster of flowers so I can sit, while I unroll my long tongue and sip nectar.
I am a moth. I like flowers that are light in color and have a strong, sweet smell since they are easier to find at night when I am active. I can hover when I eat, so I don’t need to land. My long tongue can reach into tubes to find the nectar I love to drink.
I am a bat. I have a big appetite, so I need a flower with lots of nectar and pollen. I like light-colored flowers with a strong sweet or spicy smell because they are easier to find at night when I’m flying about.
I am a carrion fly. I love smelly things, like dead fish and rotting meat. I am attracted to red, since it looks like the rotting meat where I love to lay my eggs!
I am a beetle. I don’t fly well, so I like flowers with large petals and lots of landing space. I like pale colors and sweet, fruity smells. I like to eat pollen, so the flowers I visit always have extra for me!
**When formatting these cards add a picture of the pollinator.
**Add an attachment that shows different styles of flowers – tubular, landing platform (daisy), insect guides, etc.