Which part of the plant leaf is modified to form spines of Acacia and the sheath covering the leaf of Ficus elastica?

Explanation

To answer the question regarding which part of the plant leaf is modified to form spines in Acacia and the sheath covering the leaf of Ficus elastica, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Plants**: We are dealing with two specific plants: Acacia and Ficus elastica.

2. **Understand Leaf Structure**: In flowering plants, leaves typically consist of a blade, petiole, and stipules. Stipules are small leaf-like structures that are found at the base of the leaf stalk (petiole).

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