What are annual rings ?

Explanation

**Step-by-Step Solution:**

1. **Definition of Annual Rings**: Annual rings, also known as growth rings, are layers of wood produced by trees during a year of growth. Each ring represents one year of growth.

2. **Formation Process**: Annual rings are formed in two distinct seasons of the year. In the early part of the growing season, trees produce a lighter-colored wood known as early wood. This wood is characterized by having more living tissues.

3. **Late Season Wood**: As the season progresses into the late part, the tree produces darker-colored wood known as late wood. Late wood is denser and contains more lignin, which contributes to its darker color and structure. This wood has fewer living tissues compared to early wood.

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