Selaginella and Salvinia are considered to represent a significant step toward the evolution of seed habit because
Megaspores possess endosperm and embryo surrounded by seed coat
Embryo develops in female gametophyte which is retained on parent sporophyte
Female gametophyte is free and gets dispersed like seeds
Female gametophyte lacks archegonia
A seed is made up of an embryo, stored nutrients or food, and a seed coat. The seed habit serves as the most complicated and evolutionary beneficial method of sexual reproduction. Since embryos grow in female gametophytes and are kept on parent sporophytes, Selaginella and Salvinia are thought to be crucial steps in the evolution of seed habit.