Final answer:
In seed plants, male and female embryos are nurtured within the parent sporophyte. Seed plants are heterosporous and have evolved to have a dominant sporophyte generation with a reduced gametophyte generation that remains attached to the sporophyte, allowing them to thrive in varying environments.
Step-by-step explanation:
In all seed plants, male and female embryos develop within the parent sporophyte and are completely dependent on it for nutrition and water. In seed plants, there is a distinct trend toward a dominant sporophyte generation and a reduced size of the gametophyte generation. Unlike seedless vascular plants where the gametophyte can be an independent entity, in seed plants the female gametophyte is reduced to a few cells within the spore that remains attached to the sporophyte. This spore, which develops into the gametophyte, is not dispersed but germinates in place.
Seed plants are heterosporous, meaning they produce two types of spores: megaspores (female) and microspores (male). The megaspores give rise to female gametophytes that eventually produce eggs, while microspores develop into male gametophytes that produce sperm. These gametophytes are protected and nurtured by the sporophyte, illustrating a significant evolutionary advantage as it allows these plants to thrive in a variety of environmental conditions.
Consequently, seed plants do not rely on water for reproduction as their ancestors did. The pollen grains and seeds allow for the survival and spread of the plant species over substantial distances, contributing to the success of seed plants in diverse habitats.