Why do lower vascular plants reproduce with spores instead of seeds?

Lower vascular plants, such as ferns, horsetails, and lycophytes, reproduce via spores rather than seeds because they represent an evolutionary lineage that relies on a different reproductive strategy known as the pteridophytic life cycle.12

In these plants, the sporophyte generation produces spores that are released into the environment to develop into independent gametophytes. Unlike seed plants, which retain the embryo within a protective seed coat on the parent plant, lower vascular plants disperse their offspring as single-celled spores before an embryo is formed.134

This reliance on spores is a fundamental characteristic of their life history, which requires water for the flagellated sperm to swim to the egg during fertilization. While seed plants have evolved more complex structures—including seeds that provide food reserves and protection for the embryo—lower vascular plants continue to utilize the spore-based system that has persisted throughout their evolutionary history.154