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BOTANY: PRINCIPLES AND PROBLEMS 



the water and there germinate. The megaspore produces a small 

 female gametophyte still contained largely within the thick 

 spore wall, and at the point where the wall bursts a single archego- 

 nium appears. The microspore gives rise to a single antheridium, 

 which liberates into the water a group of sperms. The young 

 sporophyte which develops from the fertilized egg is nourished 



Fig. 206. Fig. 207. 



Fig. 206. — Marsilia. The spore-fruits or sporocarps (s) growing out from the 

 petiole of the leaf contain microsporangia and megasporangia. (From Stras- 

 burger, after Bischoff). 



Fig. 207. — A club-moss (Lycopodium) . The underground stem has sent up 

 a much-branched shoot on which are the small, scale-like leaves. Upon this 

 are borne two groups of cones. 



for a time on the abundant supply of food stored in the female 

 gametophyte, but soon becomes independent through the 

 establishment of a root and leaf of its own. This heterosporous 

 type of reproduction is the highest found among the Filicineae. 

 Lycopodineae or Club Mosses. — This group is by no means as 

 rich in species as the ferns. The sporophyte (Fig. 207) has a well 

 developed stem, typically prostrate or subterranean but sending 

 up numerous erect branches which sometimes reach a decimeter 

 or more in height. In contrast to the ferns, the leaves are very 

 small, numerous, and crowded closely on the stems, presenting a 



