XIII 



LYCOPOD1NEM 



523 



phylls differ but little in appearance from the ordinary leaves, 

 but in the heterophyllous ones they are smaller than the other 

 leaves, and form a strobilus much like that of Lycopodium, but 

 usually less conspicuous. 



The strobilus (Hieronymus (i), p. 653) may be either 

 erect or horizontal ; much more rarely it is pendent, and there 

 appears to be a certain relation between the arrangement of the 

 sporophylls and the position of the strobilus. Where it is up- 

 right the sporophylls are all alike, and disposed radially about 

 the axis. Where the strobilus is horizontal it is more or less 

 markedly dorsiventral in structure. In S. selaginoides and S. 

 deftexa there is a more or less perfect spiral arrangement of the 



A 



ma 



FIG. 302. A, Part of a fruiting plant of Selaginella Kraussiana, X3; sp, sporangial 

 strobilus; R, young rhizophore; B, longitudinal section of the strobilus, X5', ma, 

 macrosporangium ; mi, microsporangium. 



sporophylls, but in all the other species they are four-ranked. 

 Usually in the latter case the sporophylls are alike, but there 

 may be the same difference in the dorsal and ventral leaves of 

 the dorsi-ventral strobili that is found in the sterile shoots of the 

 same species. 



The basal leaves of the strobilus may be sterile, but usually 

 each sporophyll subtends a sporangium. In S. Kraussiana, 

 and many other species of the same section of the genus, there 

 is but a single macrosporangium developed the first formed 



