LTCOPODIN^. 



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. — A, longitudinal section of a young prothalliura of Lycopodiwm anno* 

 iinum ; an, two antheridia^not mature — upon its lower surface are peen the root- 

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

 nation of the young plant ; «, stem of young plant ; r, its young root ; f, the foot, or 

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

 magnified.— After Fankhauser. 



Fig. 375. — Plant (asexual generation) of Lyeopo'lium cla/satwm; horizontal stem 

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

 —After Prantl. 



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

 veloped a few spermatozoids. 



494. — Three orders of Lycopodinse may be distinguished, 

 as follows : 



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



Order 1. Lycopodiacese, with small leaves, commonly 

 moss-like. 



II. Heterosporem. — Spores of two kinds ; ligules present. 



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



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



