156 
STRUCTURE AND LIFE HISTORIES 
bearing leaves are called sporophylls, and plants that bear 
sporophylls are called sporophytes. 
144. Types of Foliage-leaf. In some ferns the foliage- 
leaf presents a simple, unbranched blade, and petiole; 
but in other species the blade is variously branched. In 
such cases the larger, primary divisions are called pinna, 
FIG. 1 1 6. Fern leaves, showing various degrees of subdivision or branch- 
ing of the blade. A, Phyllitis; B, Poly podium; C, Pteris; D, Adiantum. 
and the secondary subdivisions pinnules. Illustrations 
of these various types are shown in Fig. 116. 
145. Sporangia. As noted above each sporangium con- 
sists of a spore-case borne on a stalk (Fig. 117). The struc- 
ture of the case varies considerably in various groups of 
ferns, but it usually possesses walls only one cell thick, with 
