Bud scales are modified leaves that are usually tough and overlapping, forming a protective layer around the delicate tissues within the bud. They help to:

* Protect from cold and frost: Bud scales act as insulation, preventing the bud from freezing during cold weather.

* Prevent desiccation: They help to retain moisture, protecting the bud from drying out.

* Protect from herbivores: The tough, overlapping scales make it difficult for animals to access the delicate tissues within the bud.

Once the bud is ready to open, the bud scales fall off, revealing the new leaves, flowers, or stems within.