Haploid vs Diploid

The life cycle of simple aquatic plants is dominated by the haploid phase which produces gametes that are dependent on a watery environment to meet and fuse.

The life cycle of complex land plants is dominated by the large, diploid sporophyte. Cells within the sporophyte undergo meiosis to give rise to haploid spores. Spores develop into gametophytes, that produce gametes.

The spores of some algae and simple vascular plants are all alike which is called homosporous. In the gymnosperm and angiosperm lineages, the spores are differentiated into two types which is called heterosporous.

The male gametophytes called pollen grains (as in the minute particles which cause so many allergies for those of us living in Davis) are released from the parent plant to be carried by various means (but without water) to the female gametophyte.

The female gametophytes remain in the plant and are surrounded by protective tissues, and eventually produce a seed with a protective coat that can withstand hostile conditions.

Over time the sporophytes, while developing extensive root and shoot systems, began holding onto their spores and gametophytes, protecting and nourishing them.

REVIEW: In the life cycle of primitive plants, which stage predominates?
Answer haploid stage