7 ait 
vu 
PTERIDOPHYTA 385 
The Pteridophyta are divided into three classes: Filicineae 
(ferns), KHquisetineae (horsetails), and Lycopodineae (club 
mMOSsses ). 
CLASS FILICINEAE (FERNS) 
Sporophyte. I'he sporophyte of ferns (Fig. 423) varies greatly 
in size, ranging from small mosslike species to the tall tree ferns. 

Fig. 426. Cross section of a fern stem (Gleichenia) showing protostele 
Note that the stele is solid and is concentric, that is, the xylem is surrounded 
by the phloém. Outside the stele is the cortex. (x 50) 
The structure and appearance also vary greatly in different cases. 
The sporophyte of typical ferns has a fair-sized stem, leaves 
(Fig. 424), and numerous roots. 
The characteristic type of vascular bundle in the stems of ferns 
is concentric (Fig. 425), the xylem being surrounded by phloem. 
The most primitive type of stele is a protostele (Fig. 426), or 
