Identify $X$ from the figure.

Heterospory,i.e.,the formation of two types of spores—microspores and megaspores—is a characteristic feature in the life cycle of a few members of pteridophytes and all spermatophytes. Do you think heterospory has some evolutionary significance in the plant kingdom?

One character common for $Selaginella$ and fern is

Which of the following is considered an important step for the development of seed habit?

What is a fernery?

The stele in the rachis of $Pteris$ is