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TEXTBOOK OF BOTANY 



The gametophyte. From the germinating spore of Lycopodium cylin- 

 drical, tuberous, or fleshy thalloid gametophytes develop, either under- 

 ground and without chlorophyll, or partly aboveground and green ( Fig. 

 316). They are thus partly saprophytic or parasitic on fungi. These 

 gametophytes are very minute, rarely more than a few millimeter in 

 length. The antheridia and archegonia are borne at the apex of the 

 gametophytes. The sperms are straight, uncoiled, and biciliate. Fertiliza- 

 tion of the egg by the sperm occurs in the same manner as in ferns. 



As noted above, two kinds of gametophytes develop from the spores 

 of Sela^inella. Male gametophytes develop within microspores, and 



Fig. 317. Selaginella: A, vegetative branch with terminal cone; B, longitudinal 

 section of cone with microsporangia on one side and megasporangia on the other; 

 C, female gametophyte protruding from the megaspore wall with several arche- 

 gonial openings located near the evident rhizoids; D, male gametophyte within 

 the microspore wall; E, male gametophyte with sperms formed in the cells; F, 

 section of female gametophyte and two embryos following fertilization. 



female gametophytes develop within the megaspores. Both the male and 

 the female gametophytes are small and are largely contained within the 

 old spore walls (Fig. 317). The male gametophyte consists of a vegeta- 

 tive cell and a single antheridium. The sperms formed are few in number 

 and are similar to those of Lycopodium. The female gametophvte is 

 multicellular and at first is contained within the megaspore. Subsequent 



