Plant Science: Investigating Flowers

Not all plants have flowers, but those that do are widespread and abundant. Flowers are important because they attract pollinators and are where the seeds develop.

Our post today is inspired by the children's picture book Flowers Are Calling by Rita Gray and illustrated by Kenard Pak.

With lightly-humorous, rhyming text, the author encourages children to compare kinds of animals that are attracted to flowers and serve as pollinators with animals that are not likely to be pollinators. Is a snake a pollinator? "No, not a snake, for goodness sake!" For a full review of the book see our sister blog, Wrapped in Foil.

As Rita Gray points out, pollinators are attracted to different aspects of the flower such as color, shape, time of opening, and smell. Let's investigate flower shape and color with a series of activities.

Flower petal number and shape

Some flowers look different from others based on the number of petals they have.

Desert-rosemallow-flower05Simple dicot plants (those with two cotyledons) often have flowers with 5 petals, or petals in multiples of 4 or 5. If you've forgotten which flower parts are petals, check the diagram below.

decent-orchid-tree-flower-kyreneHow many petals does this orchid tree flower have?

sorrel-flower-101How about this sorrel flower?

lesquerella-flowersHow many petals does this flower have?

lesquerella-bee-flowerThe lesquerella plant is still a dicot, even though its flowers only have 4 petals.

garlic-chive-flower

Plants like grass, corn, rice, and chives are monocots. They often have flower petals in multiples of 3. This garlic chive has flowers with 6 petals (3 x 2).

common-toadflax-flower-1Sometimes the flower petals are modified into different shapes, however, so it isn't as easy to count them. Pollinators must push their way into a closed flower like this.

AA-honeybee-going-into-snapdragon-3Check out this honey bee pushing its way into a snapdragon flower.

aster-flower-close-oursSometimes what appears to be a flower is really a cluster of small flowers. Although this aster looks like a single flower, botanically speaking it is a group of flowers. See the recent zinnia flowers and their structures post for more details about this, as well as instructions for a classic flower dissection activity.

Activity 1:  Flower Petal Counting

Go on a walk through a garden or natural area. Check the flowers and count the number of petals for each kind. Older children might want to record the type of flower and number of petals in a notebook. Relate the flower shape to what kind of pollinators visit the plant, using Flowers Are Calling or a similar book as a reference.

Extension:  Press flowers and organize them by number of petals. What patterns do you see?

Activity 2:  Design a novel flower

Using colored pencils or crayons, design a new type of flower. Remember that flowers attract pollinators and produce seeds, so be sure to incorporate the parts of the flower shown below.

Mature_flower_diagram.svg

(“Mature flower diagram” by Mariana Ruiz LadyofHats. Public Domain image at Wikimedia Commons.)

BBC also has an online flower dissection to investigate

Flower color activities

Whether or not a pollinator is attracted to a specific flower can depend on what color it is. For example bees don't see red, but birds do. Red flowers are often pollinated by birds.

Activity 3: Changing flower color with food dye

We humans like brightly-colored flowers. In fact, florists may dye white or pale flowers like roses, daisies, Queen Anne's lace, or carnations to make them more attractive.

This video shows how:

If your flowers don't change color, the xylem may have been blocked when the stem dried out. Try cutting off the stem to create new openings to the xylem.

Activity 4. Changing flower color with chemistry

Some flowers have pigments that are sensitive to changes in pH.

Gather:

  • Fresh red, blue or purple flowers (deep purple petunias work really well)
  • Jar with a lid big enough to hold a few flowers
  • Twist ties, string or yarn to suspend the flowers
  • Household ammonia
  • Vinegar and a bowl (optional)

Caution:  Ammonia is pretty strong, so this activity will require help and supervision from an adult. Be sure to follow all safety instructions on the product label. Do not mix the ammonia and vinegar together.

Have an adult pour about 1/2-inch ammonia into the bottom of the jar. Wrap a twist tie or tie yarn around the stems of a few flowers, enough that will fit comfortably into the jar. Suspend the flowers upside-down into the jar so that they are close to, but not touching the ammonia. Wrap the yarn or twist tie over the lip of the jar to keep the flowers suspended. Put the lid on the jar as tightly as possible. Leave the flowers in the jar about 15 minutes and then check to see if there are any changes.

Once the flowers have changed color nicely in the ammonia (which is a base) then try to change the color back by removing the flowers from the jar (without touching the ammonia) and dipping them in a bowl of vinegar, which is an acid.

Expected results:  Purple petunias will probably turn bright blue-green or teal in the ammonia, and then back to purple in the vinegar. You can actually dip the flowers into the vinegar because it won't bleach. If you dip the flowers into the ammonia, however, it may bleach or discolor them, which is why they need to be suspended in the ammonia fumes in the jar instead.

Flower pigment chromatography

Another way to explore the pigments in flower petals is to separate them via chromatography. Scientific American has instructions for using chromatography to investigate flower petal color.

________________

Our featured book, Flowers Are Calling, has been nominated for a 2015 Cybils award in the Elementary/Middle Grade Nonfiction category.

Age Range: 4 - 7 years
Publisher: HMH Books for Young Readers (March 3, 2015)
ISBN-10: 0544340124
ISBN-13: 978-0544340121

Disclosures: This book was provided by my local library. I am an affiliate with Amazon so I can provide you with cover images and links to more information about books and products. As you probably are aware, if you click through the highlighted title link and purchase a product, I will receive a very small commission, at not extra cost to you. Any proceeds help defray the costs of hosting and maintaining this website.


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Plant-Science-Lessons

To see our complete plant science lessons, either visit the plant science category (newest posts to oldest posts) or the plant science section of our experiment archive page (links to posts in order).

Looking for books about plants for children? Be sure to visit our growing list of gardening and plant science books for kids, as well as our list of children’s books about seeds.

For more activities, try our Gardening/Plant Science for Kids Pinterest board.

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