The plant cells that absorb water and swell up are called parenchyma cells.

Here's why:

* Parenchyma cells are the most common type of plant cell. They have thin cell walls and a large central vacuole.

* The large vacuole is key for water absorption. As water enters the vacuole, it exerts pressure on the cell wall, causing the cell to swell.

* This process, called turgor pressure, is essential for maintaining the plant's shape and structure.

While other plant cells can absorb water to some extent, parenchyma cells are the primary water storage cells in plants.