Part a the adaptation that made possible the colonization of dry land environments by seed plants is most likely the result of the evolution of pollen.
The main advantage of seed plants (Gymnosperms and Angiosperms) is the evolution of the seed which, unlike spore-producing plants, was not limited to wet environments. Pollen grains are male gametophytes (sperm) which are protected from desiccation and can reach the female organs without dependence on water. The sperm is transferred from the pollen through the pollen tube: an extension of a cell within the pollen grain. The process is called pollination.