456 



BOTANY 



PART II 



scale leaves the sporophylh are developed in whorls, but are closely aggregated at 



\ 



Fio. 420. Kquisetum arvense. A, Fertile shoot, springing from the rhizome, which also bears tubers ; 

 the vegetative shoots have not yet unfolded. F, Sterile vegetative shoot. B, C, Sporophylls 

 bearing sporangia, which in C have opened. D, Sjx>re showing the two spiral bands of the 

 perinium. E, Dry spores showing the expanded spiral hands. (A, F, i nat. size. /;. r, 7), K, 

 enlarged.) 



the tips of the erect fertile shoots into a cone (Fig. 420), which is .sometimes 

 spoken of as a flower, from the correspondence in its structure to the male flower 



