214: 



A TEXT-BOOK OF BOTANY 



that become very thick and hard (Fig. 204, A), and that 

 are packed closely together until they spread apart to let 

 out the seeds (Fig. 202, c). On the upper side of each 

 sporophyll, near its base, there are two sporangia (Fig. 204, 

 B and C), in each one of which there is a single large spore 

 (megaspore). So large is the spore that it looks like a 



FIG. 203. Staminate cone of pine: A , section of cone, showing sporophylls (stamens) 

 bearing sporangia (pollen sacs); B, longitudinal section of stamen, through one 

 pollen sac; C, cross-section of stamen, showing both pollen sacs; D, the winged 

 pollen grain. After STRASBURGER. 



conspicuous cavity in the center of the sporangium. These 

 structures also bear old names that may be used. The 

 sporangia were called ovules ; and the sporophyll bearing 

 them was called a carpel. The large spore was regarded 

 only as a cavity in the ovule. The cone, therefore, is a 

 group of carpels; and to distinguish it from the staminate 

 cone it may be called the carpellate cone. 



