Since plant cells do not have centrioles, how do they make spindle fibers during mitosis?

Spindle formation in plants is very different from most other eukaryotes owing to the fact that plant cells lack centrosomes or spindle pole bodies, which act as the microtubule organizing centers in animal cells. The evolutionary advantage that animal cells gain due to the presence of centrosomes is the ability to direct drastic changes in their shapes during mitosis.