Here's why:

* Palisade cells are found in the mesophyll layer of leaves. The mesophyll is a tissue specific to plants, responsible for photosynthesis.

* Palisade cells are characterized by their elongated shape and abundance of chloroplasts. Chloroplasts are organelles found only in plant cells, and they are the sites of photosynthesis.

Animal cells do not have chloroplasts or perform photosynthesis.