Heterospory is found in

What is the nature of the gametophytic stage in Pteridophytes?

The stele found in ferns is known as:

Which of the following pteridophytes exhibits secondary growth?

$A$ collection of sporangia attached to the placenta and covered by an indusium is known as:

Apical growth of the lower vascular plants takes place by an apical cell. This cell is generally pyramidal. Though four-sided in shape,it is often referred to as a three-sided cell because