Calyx in Flowers: Definition & Form

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  • 0:01 What is a Calyx?
  • 0:52 Formation of the Calyx
  • 2:08 Lesson Summary
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Lesson Transcript
Derrick Arrington

Derrick has taught biology and chemistry at both the high school and college level. He has a master's degree in science education.

Expert Contributor
Christianlly Cena

Christianlly has taught college physics and facilitated laboratory courses. He has a master's degree in Physics and is pursuing his doctorate study.

If you look closely at a flower, you will see that it is composed of many parts. One of these crucial parts is called the calyx. In this lesson, we will learn the definition of a calyx and how it functions in the life of a flower.

What Is a Calyx?

In many species of flowers, the calyx consists of leaf-like structures at the base of a flower that protect the flower during development. The leaf-like structures are individually referred to as sepals. There are often as many of these sepals as there are petals. While most calyces are green, there are exceptions in which the calyx is the same color as the petals of the flower or a different color altogether.

The calyx performs a crucial role for the flowering plant. As the flower is forming, it is closed tightly into a bud. The sepals are the outer covering of the flower as it forms and are the only thing you see of the flower while it is still in bud form. It protects the developing flower and prevents it from drying out.

Formation of the Calyx

The calyx is the first part of a flower that develops and is attached directly to the stem of the plant. Petals form inside the calyx along with the other parts of the flower. The sepals of the calyx are often arranged so they form an alternating pattern with the petals once the flower opens. It may be easier to think of the tightly closed calyx as a nursery for the developing flower. The flower is tightly enclosed in the calyx until it has completed development and is prepared to open.

After flowering, many plants have no more use for their calyx, and it begins to wither away; however, in some flowers, the calyx becomes thorny or hairy and remains as a means of defense against insects that would climb up the plant.

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Additional Activities

Calyx in Flowers: Puzzle and Discussion Questions

Crossword Puzzle

With a pen, draw the crossword puzzle diagram. Complete the crossword by filling in a word that fits each clue. You may use a pencil and an eraser for this activity.


1. In its development, the calyx is attached directly to the _____ of the plant.

3. Individually, this encloses the petals and forms a protective layer around a flower bud.

4. Some plants form a _____ calyx as protection for its fruit or seeds.


2. This forms along with all other parts of the flower inside the calyx.

5. A collective term for sepals at the base of the flower.

6. The form and orientation of the sepals from flower to flower often _____.

Discussion Questions

Give a brief and concise explanation for each of the following questions.

  1. As a flower blooms, its petals are often supported by the calyx. The petals surround the reproductive part of the flower and attract pollinators for reproduction. From their difference in functionality, petals and sepals are also considered to be modified leaves. Why do you think this is the case?
  2. Birds and insects often enjoy eating fruit and sucking juices from various plants. In the case of Hibiscus trionum, how does this type of plant protect its seed?

Answer Key: Crossword Puzzle

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