438 PHARMACEUTICAL BOTANY 
tion of the shoot axis and bears numerous whorls of sporophylls. 
Each sporophyll consists of a short stalk and a disk; the latter is 
arranged in peltate fashion on the end of the stalk and bears a 
number of sporangia on its lower surface. Within these sporangia 
are produced numerous spores which are liberated upon the 
jn epyens 
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Fic. 329.—Equisetum arvense. P, sterile branch; P', fertile branch with strobilus, 
or cone; R, rhizome (underground); 7, cross-section of cone, showing insertion of 
sporophylls in a whorl; V, V1, sporophylls with pendant sporangia; S, S, S?, spores 
with coiled elaters (el). (Gager.) 
ripening of the sporangia. While alike as to size, some of them 
give rise upon germination to male prothallia, others to female 
prothallia. These prothallia represent the sexual or gametophyte 
plants. The male prothallia produce antheridia along the margins 
or tips of their lobes in which, when mature, numerous many- 
ciliated antherozoids are found. ‘The female prothallia produce 
