272 INTRODUCTION TO BOTANY 
and no such description is here attempted. In all leaves the 
fibrovascular bundles extend throughout the leafstalk into 
the leaves, where they are known as the veins of the leaf. 
Fie. 209. The rootstock of a fern 
The outer part of the stem is made up of hard tissue, and in the interior are also 
bundles of hard tissue (s) known as sclerenchyma; numerous woody bundles (f.b) 
are also surrounded by the large amount of pith 
Fie, 210. Diagram of cross section of a fern leaf 
On the underside of the leaf are the indusium (i) and the sporangia (s); within 
the sporangia are the spores. After Engler and Prantl 
