STRUCTURE 



443 



The leaves (Fig. ii6, a) arise in four longitudinal rows, 

 but, owing to the horizontal position of the plant, the two 

 rows belonging to the lower side (Z^) project laterally, and 



Fig. ii6. — a, distal end of a shoot of Selaginella, showing the two 

 rows of small dorsal leaves (/'), the two laterally placed rows of ventral 

 leaves (/^), and the terminal cone (c). (Nat. size.) 



B, a microsporangium bursting to allow of the escape of the micro- 

 spores (mi. sp). 



c, a megasporangium, with four megaspores (mg. sp). 



(a, after Sachs ; B and c, after Le Maout and Decaisne. ) 



uiv many times larger than the two upper rows (/^). Each 

 leaf bears on its upper or distal surface, near the base, a 

 small process called a li^ulc. 



I'he stem usually ends in u two- or three-sided apical 

 cell, from w'hich segments are cut off to form the apical 



