Leaf of which of the following plants shows circinate vernation at the young stage?

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

The characteristic feature of a fern is:

Some genera like $Selaginella$ and $Salvinia$ produce two kinds of spores. What are such plants called?

Trabeculae in $Selaginella$ stem represent

In $Dryopteris$ (fern),the permanent roots are .........