That's a tricky question! All plant cells, and in fact all eukaryotic cells, have a nucleus.

The nucleus is the control center of the cell, containing the genetic material (DNA) and directing all cellular activities.

Perhaps you're thinking of a different type of cell? Maybe you're thinking of prokaryotes? Prokaryotes (like bacteria and archaea) are single-celled organisms that lack a nucleus and other membrane-bound organelles. They have a single, circular DNA molecule located in a region called the nucleoid, but it's not enclosed within a membrane.