Difference Between Involucral Bract Calyx and Indumentum

The key difference between involucral bract calyx and indumentum is that involucral bract is the bract that appears in a whorl while calyx is the collection of sepals and indumentum is the surface covering composed of hairs or trichomes in plants.

Bract, calyx and indumentum are three parts of plants.  The involucral bract is the conspicuous bract or a whorl of bract seen at the base of an inflorescence. Calyx is the collection of sepals of a flower. Indumentum is the hairy covering of plants. All three parts are important for plants, and they carry out several functions in plants.

CONTENTS

1. Overview and Key Difference
2. What is Involucral Bract 
3. What is Calyx 
4. What is Indumentum
5. Similarities Between Involucral Bract Calyx and Indumentum
6. Side by Side Comparison – Involucral Bract vs Calyx vs Indumentum in Tabular Form
7. Summary

What is Involucral Bract?

Involucral bract is the conspicuous bract or whorl of bracts present at the base of an inflorescence. The bract that is present in the form of a whorl is known as the involucral bract. It is a leafy structure. Each individual flower of the inflorescence has its own involucel. Involucral bract is a common feature of several families of flowering plants like Asteraceae, Apiaceae, Euphorbiaceae and Proteaceae.

Involucral bract is a good characteristic that can be used to distinguish flowering plants. Moreover, it protects the developing nuts.

What is Calyx?

Calyx is the collection of sepals. It is the outermost whorl of a flower. Calyx resembles leaves because most flowering plants have green colour sepals. However, some flowers have colourful sepals as well. Brightly coloured calyx sometimes functions as petals to attract pollinators. In some plants, sepals remain separate. But some plants have marginally fused sepals.

Generally, the number of calyx lobes is equal to the number of fused sepals. The major function of the calyx is to protect the unopened flower bud. Unlike petals and stamens, the calyx is persistent. It can be seen even in fruits.

What is Indumentum?

Indumentum is the hairy covering of plants. It may include trichomes. Indumentum can be seen on the underside of the leaves. Indumentums can also be seen in the stems and petioles. Presence or absence of an indumentum is a vegetative character used in plant identification.

Indumentum fulfils several functions in plants. It acts as an anchorage in climbing plants. Moreover, it prevents transpiration and helps in water absorption. It also protects plants from insect predators. Most importantly, in some plants, indumentum helps in the trapping of insects.

What are the Similarities Between Involucral Bract Calyx and Indumentum?

• Involucral bract, calyx and indumentum are three parts of plants.
• All three structures are useful for plants.

What is the Difference Between Involucral Bract Calyx and Indumentum?

Involucral bract is the whorl of bracts present at the base of an inflorescence while calyx is the collection of sepals of a flower. Indumentum, on the other hand, is the surface covering of hairs or trichomes in plants. So, this is the key difference between involucral bracts calyx and indumentum.

Moreover, involucral bract protects the developing nuts, while calyx protects the unopened flower bud, and indumentum controls transpiration, water absorption, provides an anchorage, etc. Thus, this is the functional difference between involucral bracts calyx and indumentum.

Summary – Involucral Bracts Calyx vs Indumentum

Involucral bract is a bract arranged in a whorl at the base of an inflorescence. It protects the developing nuts. Calyx is the collection of sepals of a flower. It protects the unopened flower bud. Indumentum is the hairy surface covering of plants. It controls transpiration, water absorption. It also acts as an anchorage to climbing plants. Thus, this summarizes the difference between involucral bract calyx and indumentum.

Reference:

1. “Bract”. En.Wikipedia.Org, 2020, Available here.
2. “Angiosperm – Reproductive Structures”. Encyclopedia Britannica, 2020, Available here.
3. “Indumentum”. En.Wikipedia.Org, 2020, Available here.

Image Courtesy:

1. “Grindelia squarrosa involucral bracts” By Matt Lavin (CC BY-SA 2.0) via Flickr
2. “Abutilon megapotamicum250060473” By f99aq – originally posted to Flickr as trailing abutilon (CC BY-SA 2.0) via Commons Wikimedia
3. “EchiumVulgare-stengel-hr” (CC BY-SA 3.0) via Commons Wikimedia