Tag: plant science

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Flower Dissection: try this simple hands-on science activity in your classroom!

pink flower, tweezers, and scissors with worksheets.

Are you teaching your students about the parts of a flower or plant anatomy? Sometimes the best way to understand how something works is by taking it apart. A flower dissection is a simple and engaging hands-on activity that brings plant anatomy to life in your classroom. In this activity, students will carefully examine and identify key flower structures like petals, sepals, carpels, and stamens. Plus, they’ll explore the fascinating connection between flowers and Fibonacci numbers in nature!

If you’re looking for more background information about flower anatomy, be sure to check out my blog post where I cover the four main whorls of a flower. You can also learn more about the functions of flowers and their various parts in the plant life cycle in this post about pollination and the plant life cycle!

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Please Note: I’ve made the directions for this flower dissection activity available for free here in this post. If you would like printable directions and worksheets for this activity, you can find them in my complete Flowers Unit in my shop.

Materials

Each student will need the following materials:

  • Flowers
  • Tweezers
  • Glue
  • Pencils or pens
  • Printed student directions and lab worksheet (available in my Flower Unit)

Tips for Success

  • Have flower and plant anatomy diagrams on hand so your students can reference them as they dissect their flowers.
    • You can find my hand-drawn flower & plant anatomy diagrams in my flowers unit (linked above)
    • You can also find a free flower diagram on my free resources page (pictured below)!
  • Use a large flower so that students can easily see all the parts.
  • Use a complete flower with all four main flower parts: sepals, petals, carpels, and stamens. For example, lilies, hibiscuses, or tulips are all good choices.
diagram showing the parts of a flower

Directions

Part 1: Flower Dissection

Pass out the materials to your students. Give a brief overview of the main parts of a flower. Then, assist your students as they work through the following steps to dissect their flowers:

  1. Use the tweezers or your fingers to carefully remove the sepals and then the petals from your flower.
  2. Break apart the carpel(s) and stamens.
  3. Count the number of sepals, petals, carpels, and stamens and record the number of each.
  4. Glue one of each part to the lab worksheet.
  5. Use a pencil or pen to draw arrows and label the stigma, style, and ovary on the carpel glued to the lab worksheet.
  6. Use a pencil or pen to draw arrows and label the anther and filament on the stamen glued to the lab worksheet.

Part 2:  Fibonacci Numbers in Nature

Fibonacci numbers form a sequence so that each number is the sum of the previous two numbers (e.g., 1+1 = 2; 2+1 = 3, 3+2 = 5; 5+3=8; and so on). Fibonacci numbers are often found in nature. Students should answer the following questions:

  1. Calculate and write down the next 5 numbers in the Fibonacci sequence: 1,1,2,3,5,8,… ___, ___, ___, ___, ___
  2. Look back at your lab worksheet. How many petals did your flower have? Is this a Fibonacci number? What about the sepals? Carpels? Stamens?

Study Flowers with Wild Earth Lab!

If you enjoyed this activity, I know you’ll love my Flowers Unit! It includes everything you need for this activity and other flower projects too!

OR – take your botany learning to the next level with my Botany Collection. It’s a bundle of three plant units: Flowers, Pollination, and Fruit!

Ready for another dissection?

Read my blog post on how to do a Mushroom Dissection Lab!

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If you enjoyed this post, I know you will love trying my other science and nature units in your classroom too!

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The Saguaro Cactus Life Cycle: step-by-step guide with pictures!

A picture of the saguaro cactus life cycle with the text "saguaro cactus life cycle: a step-by-step guide"
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Some saguaro cacti live for 200 years or longer! Saguaro cacti grow very slowly. The speed of growth depends on many factors such as precipitation, temperature, and soil quality. Let’s explore the saguaro cactus life cycle in five steps! Notice that desert animals play a key role in two of these steps.

For Teachers and Parents: If you’re an educator planning to teach kids about cacti in your classroom or at home, great activities and visuals are key to deepening understanding! I think you and your students will love my complete Cactus Unit (plus you’ll support my blog with your purchase! ❤️)

1. Germination

Saguaro cactus seedling

A seed germinates. The two cotyledons open to form a tiny plant. Seeds that germinate in shady areas such as beneath palo verde trees are most likely to survive through the fragile young stages and reach maturity.

The seedling cactus grows through its first summer and develops more areoles and spines. At just a few millimeters in height, the seedling is so small that it can be difficult to spot.

2. Maturity

It may take ~35 years for a saguaro cactus to reach maturity and produce its first flowers.

The rate of growth depends on environmental conditions such as precipitation, temperature, soil quality, and the type of cactus. For saguaro cacti, growth happens very slowly over many years.

When a cactus reaches reproductive maturity, it can produce its own flowers. Time to reach maturity depends on the cactus species. For example, the saguaro cactus takes several decades to reach maturity.

3. Flowering & Pollination

The lesser long-nosed bat is a nighttime pollinator of the saguaro cactus

The cactus flowers bloom. Cactus flowers make tasty nectar to attract pollinators like bats, bees, and doves. Pollen is transferred between plants by the pollinators. This is a type of symbiotic relationship called mutualism because both the pollinator and the plant benefit. The pollinator gets a tasty meal of nectar, and the plant gets pollinated.

4. Fruiting

Saguaro fruits are a food source for many animals in the Sonoran desert. People sometimes eat the fruit too.

Once pollinated, the cactus fruit begins forming from the ovary of the flower. Cacti can produce huge amounts of fruit. For example, a single saguaro cactus may produce upwards of 100 fruits each year. That’s a lot of fruit! The ripened fruit splits open, revealing sweet flesh and seeds.  This sends the signal to animals that the fruit is ready to eat!

5. Seed Dispersal

When an animal eats the saguaro fruit, it ingests some seeds. The seeds are then dispersed in the animal’s scat.

Desert animals like birds, coyotes, and tortoises eat cactus fruit and disperse seeds in their scat. This is another example of a mutualistic relationship between an animal and a cactus. The animal gets a meal of fruit, and the cactus gets its seeds dispersed. If the cactus is lucky, some of its seeds will be deposited in locations with good growing conditions. Over its lifespan, a single saguaro may produce millions of seeds. However, only a few of those seeds will germinate, grow, and reach maturity.

Classroom cactus materials:

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References and Further Reading

  1. Ceotto, E. (2009). Cultivation of Carnegiea gigantea from seeds: a journey in desert ecology. Desert Plants, 25(1), 10. Available: https://repository.arizona.edu/bitstream/handle/10150/556548/dp_25_01-010-015.pdf?sequence=1
  2. Dimmitt, M. (n.d.). Cactaceae (cactus family). Arizona-Sonora Desert Museum. Available: https://www.desertmuseum.org/books/nhsd_cactus_.php
  3. Helmy, Olga. 2021. Carnegiea gigantea, saguaro. In: Fire Effects Information System, (Online). U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Missoula Fire Sciences Laboratory (Producer). Available: www.fs.usda.gov/database/feis/plants/cactus/cargig/all.html
  4. National Park Service (n.d.). The Saguaro Cactus (Carnegiea gigantea). Organ Pipe Cactus National Monument. Available: https://www.nps.gov/orpi/learn/nature/saguaro-cactus.htm
  5. National Park Service (2017). How Saguaros Grow. Saguaro National Park. Available: https://www.nps.gov/sagu/learn/nature/how-saguaros-grow.htm

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