L YCOPODIN^fi. 



383 



bears both kinds of sexual organs. In the heterosporous 

 genera the macrospores produce small prothallia, which 

 project slightly through the ruptured spore-wall, and upon 

 these several or many archegonia are formed ; the micro- 

 spores produce very small rudimentary prothallia, each of 



FIG. 274. 



FIG. 275. 



Fig. 274. A, longitudinal section of a young prothallium of Lycopodium anno- 

 tinum ; an, two antheridia, not mature upon its lower surface are seen the root- 

 hairs. X 150. , longitudinal section of a prothallium, p, of the same, after germi- 

 nation of the young plant ; s, stem of young plant ; r, it8 young root ; /, the foot, or 

 portion of the young plant which remains in contact with the prothallium. Slightly 

 magnified. -After Fankhauser. 



Fig. 275. Plant (asexual generation) of Lycopodium clavatum ; horizontal stem 

 with roots and leaves, the erect branch bearing fertile spikes, . One half natural size. 

 After Prantl. 



Avhich bears a single antheridium, in which there are de- 

 veloped a few spermatozoids. 



494. Three orders of Lycopodinse may be distinguished, 

 as follows : 



7. IsosporecB. Spores of one kind ; no ligules. 



Order 1. Lycopodiacese, with small leaves, commonly 

 moss-like. 



//. HeterosporecB. Spores of two kinds ; ligules present. 



Order 2. Selaginellse, with small moss-like leaves. 



Order 3. Isoeteee, with elongated grass-like leaves. 



