Ginger is an example of a modified stem.

Explanation:
Ginger is a perennial herb that belongs to the Zingiberaceae family. It is widely cultivated for its aromatic and medicinal properties. When we examine the structure of ginger, we can observe various modifications in its stem.

1. Rhizome: The underground part of ginger is a modified stem called a rhizome. The rhizome is a horizontal, fleshy, and swollen structure that grows underground. It serves as the main storage organ for nutrients and water.

2. Nodes and Internodes: The rhizome of ginger has distinct nodes and internodes. Nodes are the points on the rhizome from which leaves and roots emerge, while internodes are the spaces between the nodes.

3. Adventitious Roots: Ginger rhizomes also produce adventitious roots from their nodes. These roots grow downwards into the soil, anchoring the plant and absorbing water and nutrients.

4. Buds: Along the rhizome, we can find small buds known as "eyes." These buds give rise to new shoots and eventually develop into aerial stems.

5. Aerial Stems: From the buds, aerial stems emerge above the ground. These stems are green, leafy, and erect. They bear the leaves and flowers of the ginger plant.

6. Modified Leaves: The leaves of ginger are narrow, lance-shaped, and arranged alternately along the aerial stems. They are modified to function as food storage organs called bracts. These bracts store nutrients and provide support to the plant.

In conclusion, ginger is an example of a modified stem because its rhizome serves as the main storage organ and the source of new shoots. The nodes, internodes, adventitious roots, buds, and aerial stems are all modifications of the stem that enable ginger to propagate and survive in various environmental conditions.