Free-central placentation is found in Brassica, Citrus, Dianthus, Argemone.
Citrus.
Argemone.
Brassica.
Dianthus.
Solution:
Free central placentation is present in single chambered ovary with ovules borne on the central axis. Brassica and Argemone (parietal placentation), Citrus (axile placentation), Dianthus (free central).