366 



BOTANY. 



into four cells (C, Fig. 250), and from these the young plant 

 of the asexual generation is developed. The young plant is 

 quite simple, having small internodes, bearing sheaths which 



contain but three leaves ; lar- 

 ^^^ ger shoots soon arise, with lar- 

 *A jilHP^j ger internodes and sheaths hav- 

 ing more leaves, and these are 



followed by others still larger, 



B *iiB wmyi until at last the full size is 



reached. 



479. The spores of the 

 Equisetinae are produced either 

 upon the ordinary green stems, 

 as in Equisetum limosum and 

 E. liyemale^ov upon colorless 

 or brownish stems, which de- 

 velop early, and, after bearing 

 the spores, die and disappear, 

 as in E. Telmateia and E. 

 arvense. The sporangia are 

 developed upon mo d i fi e d 

 leaves, upon the ends of the 

 stems. The spore - bearing 

 leaves, like the ordinary ones, 

 are in whorls ; each leaf is, 

 however, peltate in form, and 

 borne upon a short stalk (st, 

 Fig. 251, B). These peltate 



leaves (usually called the pel- 

 Fig. 251. Equisetum Telmateia A i \ n . n , 

 upper part of a fertile stem, with lower tate Scales) are Collected into 

 half of the spike mat. size) ; b, sheath of pmp ,! pf i p l n ,,fpr and Tvo- 

 united leaves ; a, annulus or ring form- c ISterS, ana Dy 



mutual pressure each 



pressure 

 scale becomes more or less 



ed of imperfectly developed leaves; x, fTipir 



the pedicels of peltate scales which have 



been cut off ; y, section of the rachis of 



the spike. , peltate scales, s, s, in 



various positons (slightly magnified) ; hexagonal in Outline. Upon 



<7,the sporangia borne on the under side 



of the scales; st, st, the pedicels of the the under suriace oi each scale 



scales. After Sachs. . , 



there arise five to- nine or ten 



cellular masses, which enlarge and become sac-shaped spo- 

 rangia ; certain inner cells become spore mother-cells, and 

 from each of these four spherical spores are produced. The 



