Mention the function of (i) Underground stem of ginger (ii) Axillary bud of citrus.

Explanation

### Step-by-Step Solution

**(i) Function of Underground Stem of Ginger:**
1. **Storage of Food:** The underground stem of ginger, known as a rhizome, primarily functions to store food. It accumulates starch and other nutrients which are essential for the plant's growth and development.
2. **Vegetative Propagation:** The underground stem also plays a crucial role in vegetative reproduction. It can give rise to new plants, allowing the ginger to spread and propagate without the need for seeds.

**(ii) Function of Axillary Bud of Citrus:**
1. **Growth into Thorn:** The axillary bud in citrus plants has the ability to develop into a thorn. This transformation is a protective adaptation for the plant.
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