CRYPTOGAMS 



459 



are homosporous ; those of other Lycopodinae heterosporous. The 

 heterosporous forms produce only greatly modified and reduced 

 prothallia ; in the genus Lycopodium, on the other hand, the prothallia 

 are well developed, and resemble those of the Ophioglossaceae. In the 

 development of their sexual generation the heterosporous Lycopodinae 

 resemble in many respects the heterosporous Hydropterideae. 



The dichotomous branching of the stems and roots is characteristic 

 of this class (Figs. 18, 19). 



Order 1. Lyeopodiaeeae ( m ) 



The numerous, widely distributed species of the genus Lycopodium (Club Moss) 



FIG. 422. Lycopodium davotiim. A, Old prothallus. B, L'rothallus with .young plant attached. 

 C, Antheridium in vertical section. D, Spermatozoids. K, Young archegonium, the 'neck 

 still closed. F, Open archegoninm ready for fertilisation. G,,Plant bearing cones ( nat. size). 

 H, Sporophyll with an 'opened sporangium. J, K, Spores from two points of view. (A-F, 

 after BRUCHMANN.) 



are for the most part terrestrial plants ; in] the tropics epiphytic forms also occur. 

 In Lycopodium davatum, one of the commonest species, the stem, which is thickly 



