76 



Ehvientary Botany 



Of the parallel-veined leaves there are thr^e varieties. 

 AVhen, as in the Grass (fig. log), the veins all run from the 

 base to the apex, it is straight veined. When, as in the 

 Banana, there is a central midrib, and the side veins run off to 

 the margin, it is transverse veined. When, as in the Fan 

 Palm (fig. 72), there are several veins diverging from a common 

 centre, it is radiating veined. 



We may tabulate these forms of venation as follows : — 

 Reticulate -veined Leaves 



Unicoitate 



Multicostate 



Curved 

 veined 



Feather 

 veined 



Diverging 

 veined 



Converging 



veined 



Parallel-veined Leaves 



Straight 

 veined 



Transverse 

 veined 



Radiating 

 veined 



In describing leaves, besides the vena- 

 tion, we have to take into account the 

 following points : — i. Composition ; 2. 

 Margin ; 3. Incision ; 4. Apex ; 5. General 

 Outline. 



1. Composition. — Leaves are either 

 simple or compound. In simple leaves, 

 as in the Apple (fig. loi), there is only a 

 single lamina ; in compound leaves, as the 

 Acacia (fig. 103), the lamina is divided 

 into a number of leaflets articulated to 

 the common petiole. 



2. Margin. — The condition of this 

 depends upon the extent to which the par- 

 enchyma is developed between the veins. 

 The margin may be entire, as in Grasses. 

 More often there are indentations. 



If the teeth thus formed are rounded 

 (fig. 113), the margin is crenate. If they 

 \^fo"di7wwte Muttard are sharp, and point straight outwards (fig. 

 (Bra,nc«. alba). ^^^^^ j^ jg flentat-. If sharp and pointing 



towards the apex, like teeth of a saw (fig. 10 1), serrate. 



