Difference between Involucral Bract, Calyx and Indumentum

Involucral Bract

A bract is a modified or specialised leaf associated with reproductive structures of a plant. A whorl of bract that is present at the base of the inflorescence is referred to as an involucral bract. These bracts are inconspicuous structures that are commonly found in flowering plants such as Apiaceae and Asteraceae.

They are of different colours and shapes and can be easily distinguished from petals and sepals. The bracts serve the purpose of attracting pollinators.


The sepals are collectively termed as calyxes. They are mainly green in colour and often confused with leaves. The calyx covers the petals when they are developing and protects them.


An indumentum is the covering of trichomes on a plant. It serves the purpose of anchoring climbing plants, controlling transpiration, reflecting solar radiation and trapping insects.

Involucral Bract vs Calyx vs Indumentum

Involucral Bract




A modified or specialised leaf present at the base of inflorescence.

A collection of sepals is referred to as calyx.

The covering on trichomes is referred to as indumentum.


Present at the base of inflorescence.

Present beneath the petals.

Present on stems.


It attracts the pollinators.

It protects the developing petals.

It helps in anchoring, controlling transpiration and trapping insects.

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Frequently Asked Questions

What is the difference between bract and calyx?

Calyx is the essential whorl of sepals present beneath the whorl of petals, whereas a bract is a modified leaf structure that is seen on flower, cone scale or inflorescence axis.

What is the difference between bract and epicalyx?

A bract is a modified leaf structure found on flower or cones, whereas an epicalyx is a whorl of bracts found as an additional layer around the calyx.

Mention the types of bracts.

The nine types of bracts are: i) Leafy or Foliaceous Bract ii) Petaloid Bract iii) Spathe Bract iv) Involucral Bract v) Scaly Bract vi) Cupule vii) Epicalyx viii) Glume and ix) Lemma and Palea.

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