Here's why:

* Animal cells use centrioles for organizing microtubules, which are important for cell division (specifically, forming the spindle fibers that pull chromosomes apart).

* Plant cells have a rigid cell wall and don't use centrioles for organizing microtubules. Instead, they rely on a different mechanism involving microtubule organizing centers (MTOCs) located near the nucleus.

So, while both plant and animal cells have microtubules, the way they are organized differs, leading to the absence of centrioles in plant cells.