Kingdom Plantae is divided into Cryptogamae and Phanerogamae based on the morphology of their _____
Seeds
The Plant Kingdom is divided into 2 broad categories, Cryptogamae and Phanerogamae based on the form/morphology of their reproductive structures, i.e., flowers and the presence/absence of seeds. Cryptogams have hidden reproductive organs and don't form seeds whereas Phanerogams have well-developed flowers and seeds.