16 



STRUCTURAL BOTANY 



as we see in the leaf of a Vine or Geranium. The 

 narrow part of the blade, however, only differs from a 

 leaf-stalk in being slightly winged. The part of the 

 leaf where it joins the stem is called the leaf-lase ; 

 this remains in connection with the stem after the 

 rest of the leaf has dropped off. 



The shape of this leaf is ex- 

 pressed in botanical language by 

 the words lanceolate, acute, and 

 entire. The word lanceolate refers 

 to the general outline, which is 

 like that of a lance-head ; the word 

 acute indicates the pointed apex; 

 while the term entire means that 

 the edge is not toothed or divided 

 in any way. 



The upper surface of the leaf is 

 dark green and very slightly hairy. 

 The under surface is of a lighter 

 green, and has many more hairs. 

 The hairs are closely applied to the 

 surface, and cannot be seen well 



F,G.7.-LeafofWall- , 



flower, natural size, easily be felt 



^ving the chief The leaf is traversed from end 

 to end by a stout midrib, or 

 principal vein, which is more prominent on the lower 

 surface, and gradually tapers towards the apex, 

 From the midrib branch - veins are given off at 

 irregular intervals, which turn upwards so as to run 

 nearly parallel to the midrib. These main branches 



