There are many characteristics that have helped plant adapt to land. And there are many theories to it. Therefore I will not “list”, but I will explain the main ones:
One among them is seed and pollen production which do not need water to assist them to spread. The Pollen and seeds can be dispersed by insects, animals and wind making them easy to colonize land.
Second seeds allow for plants to stay in dormant phase in case there is no water.
Third, they developed very good vascular system, xylem especially for water transport within the plant.
In addition we now know that land plants formed symbiotic relationship very early especially with mycorrhizal fungi. This helps to take up nutrients (and even water) from soils.