In which of the following plants is the female gametophyte retained on the parent sporophyte for variable periods?

Step-by-step solution

The retention of the female gametophyte on the parent sporophyte for variable periods is a characteristic feature of heterosporous pteridophytes. The development of the zygotes into young embryos takes place within these female gametophytes, which is considered an important step in evolution as a precursor to the seed habit. Among the given options, Selaginella is a heterosporous pteridophyte. Pteris, Equisetum, and Lycopodium are homosporous pteridophytes where the gametophyte is typically free-living and independ