62 



BEC/AWEKS* BOTANY 



Fic. 74. — Dicotyledonous Stem of One Year at Left 

 WITH Five Bundles, and a two-year stem at right. 



c, the pith; c, the wood part; ^, the bast part; a, one year's growth. 



ling. As the dicotyledonous seed germi- 

 nates, five bundles are usually formed in 

 its hypocotyl (Fig. 74) ; soon five more are 

 interposed 



between 



Fig. 73. — The 

 Scattered 

 Bundles or 

 Sirands, in 

 monocotyledons 

 at a, and the bun- 

 dles in a circle in them, and 

 dicotyledons at ^. ^^^ j^^|^j_ 



plication continues, in 

 tough plants, until the 

 bundles touch (Fig. 74, 

 right). The inner parts 

 thus form a ring of wood 

 and the outer parts form 

 the inner bark or bast. A 

 new ring of wood or bast 

 is formed on stems of di- 

 cotyledons each year, and 



the age of a cut stem is 



■ -, ■, .1 Fig. 75. — FiBRo-VASCULAR Bundle of 



easily determmed. Indian corn, much magnified. 



When cross-sections of ^, annular vessel; yl', annular or spiral vessel; 



, , IT TT^ , thick-walled vessels; li^, tracheids or 



mOnOCOtyledonOUS and dl- ^oody tissue ; F, sheath of fibrous tissue sur- 



COtvledonOUS bundles are rounding the bundle ; ^7", fundamental tissue 



or pith ; S, sieve tissue ; P, sieve plate ; C, 



examined under the mi- companion cell ; /, intercellular space, formed 



. . ,., by tearing down of adjacent celL ; fK', wood 



croscope, it is readily seen parenchyma. 



