Here's why:

* Nuclear Genome: The nucleus of a plant cell contains the main genome, similar to animal cells. This genome is organized into chromosomes and contains the majority of the cell's genetic information.

* Organelle Genome: Plant cells also have a second genome located in their chloroplasts, the organelles responsible for photosynthesis. This chloroplast genome is smaller than the nuclear genome but plays a crucial role in energy production.

So, while there's a single nucleus and a single set of nuclear chromosomes, the presence of chloroplasts with their own DNA means a plant cell has two distinct genomes.