LTCOPODIN^. 



383 



bears both kinds of sexual organs. In the heterosporous 

 genera the macrospores produce small protliallla, 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.— .4, longitadiDal section of a young prothallium of Lycopodivm ann-o- 

 iinum ; an, two antheridiaj not mature— upon its lower surface are seen the root- 

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

 nation of the young plant ; s, stem of young plant ; r, its young root ; ./", the foot, or 

 portion of the young plant which remains incontact with the proihallium. Slightly 

 magnified.- After Fankhauser. 



Fig. 375.— Plant (asexual generation) of Lyeopoiium elavatum; horizontal stem 

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

 —After Prantl. 



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

 veloped a few spermatozoids. 



494. — Three orders of Lycopodinae may be distinguished, 

 as follows : 



/. IsosporecB. — Spores of one kind ; no ligules. 



Order 1. Lyoopodiacese, with small leaves, commonly 

 moss-like. 



//. Heterosporece'. — Spores of two kinds ; ligules present. 



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



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



