Answer :
The answer to the question is vascular tissue and seeds. The developmental adjustments that helped plants succeed and spread ashore were vascular tissue and seeds. They help to scatter the seeds to a more remote place which helps plants to develop somewhere else.
Many adaptations are responsible for the evolution of plats, to grow on land. This includes their ability to grow on comparatively dry lands, alternation of generations (diplod/haploid), lack of buoyancy, ability to resist dessication, ability to produce seeds and vascular system.