DEVELOPMENT OF PLANTS 315 



cent, so that the green color of the chloroplasts can be seen. 

 These reactions occur even in the dead plants and so create the 

 impression that they have returned to life. Many of the species 

 of Selaginella have a creeping habit like that of Lycopodium, 



\ 



Fig. 241. A common cultivated Selaginella: 1, habit of the plant — s, 

 strobilus; b, branch-bearing roots. \A, portion of stem, showing leaf ar- 

 rangement. — H. O. Hanson. 



and the aerial stems are covered with leaves arranged in several 

 rows, very frequently in four rows of two large and two smaller 

 leaves (Fig. 241, iA). Usually but a single chloroplast appears 

 in each cell, as already noticed in several algae and in the Antho- 

 cerotales. The roots are frequently developed from the end of 

 naked branches that extend from the stems to the ground (Fig. 

 241, r). 



(a) Sporangia and Spores. — The sporangia are borne on the 

 stems in the axils of the leaves which form a strobilus, as in 

 Lycopodium. However, they differ radically from those of the 



