220 PRACTICAL BOTANY. 



in different seeds. The embryo may be large and the 

 endosperm small, or the endosperm large and the embryo 

 small ; in some cases the endosperm is entirely wanting. 

 The embryo is a rudimentary plant/ When this rudi- 

 mentary plant begins to grow, it sends its roots down into 

 the soil and its leaves up into the air. Some plants de- 

 velop their leaves alternately; others develop them in 

 pairs. From these facts has arisen a division of the 

 Angiosperms into: 



SUBCLASS I. THE MONOCOTYLEDONS. 

 SUBCLASS II. THE DICOTYLEDONS. 



SUBCLASS I. The Monocotyledons. In the Monocoty- 

 ledons there is only one cotyledon in the embryo. The 



leaves which are 

 usually parallel- 

 veined develop 

 alternately. In 

 the stems the 

 wood is never 

 arranged in cir- 

 cles, but is 

 placed in bun- 

 dles that are 

 scattered irreg- 

 ularly through 

 the entire thick- 

 ness of the stem ; 

 in the more 

 woody stems 



FIG. 139. Transverse section of Sugar Cane. ,, 



the bundles are 



most abundant near the circumference, forming by the 

 interlacing ends of the fibers that compose them a tough 

 rind or false bark to cover the stem. The parts of the 

 flower are usually in threes ; never in fives. The flowers 



