Question

Phyllode is a modification of –
A) Petiole
B) Stem
C) Inflorescence
D) Root

Answer 1

Hint: Phyllodes are leaf like in appearance and function. They have the ability to perform photosynthesis and function as foliage. They are found on most species of Acacia trees and shrubs.

Complete answer:
In flowering plants, a petiole is generally slender and renders support by attaching the leaf blade to the stem. In some plants, petioles become modified to leaf – like structure and they carry out photosynthesis.
>Option A: Phyllodes are flat, green-coloured leaf-like modifications of petioles or rachis. The leaflets are highly reduced. Phyllodes bear an axillary bud, they do not have flowers. Therefore, this is the correct option. Example – Acacia auriculiformis (Australian acacia), Parkinsonia etc. have petioles modified into phyllodes, which is a xerophytic modification to reduce transpiration.
>Option B: There are different kinds of stem modifications - Bulb, thorns, tendrils, bulbils, etc but phyllode does not come under stem modification. Therefore, this is the incorrect option.
>Option C: Inflorescence means the arrangement of flowers on a floral axis and the various kinds of inflorescence modifications are - racemose, cymose, etc. Therefore, this is the incorrect option.
>Option D: The different kinds of root modifications are - Napiform, fusiform, conical, tuberous roots, Therefore, this is the incorrect option.

Thus, the correct answer is option (A) Petiole.

Additional information: Some more examples are,
>In Parkinsonia, the leaves are bi-pinnately compound. The primary rachis of each leaf is short and modified into spine. The secondary rachis are modified into phyllodes.
>The phyllodes of Australian acacia are pendant, have few stomata thus reduce transpiration.

Note:Many phyllodes start with tree leaves as seedlings, but they fall off after the phyllodes have developed. Phyllodes of Acacia Koa are thick and coriaceous, helping the plant in surviving in stressful environments.