The plant cells that function in providing support and are dead at maturity are sclerenchyma cells.

Here's why:

* Support: Sclerenchyma cells have thick, rigid cell walls made of lignin, a strong polymer that gives them structural support.

* Dead at Maturity: They lose their cytoplasm and organelles during development, becoming essentially hollow structures. This allows them to contribute to support without hindering the movement of water and nutrients within the plant.

There are two main types of sclerenchyma cells:

* Fibers: Long, narrow cells often found in bundles. They provide tensile strength, allowing the plant to withstand bending and stretching.

* Sclereids: Variable in shape, often found in seed coats, fruit pulp, and nutshells. They provide hardness and resistance to crushing.

Let me know if you'd like to learn more about sclerenchyma cells!