Venation 



75 



If we take the net-veined leaves, we find that there is either 

 a single principal vein or midrib, as in the Guelder Rose (fig. 

 no), when the leaf is said to be unicostate, or there are several 

 principal veins, as in the Maple (fig. io8), when the leaf is 

 multicostate. 



Again, amongst unicostate leaves in some cases the smaller 

 veins curve towards the apex (fig. no), when we may term the 

 leaf curved-veined ; in other cases they run more at right 

 angles from the midrib to the margin (fig. in), when it is said 

 to be feather-veined. /\ 



Fig. iro, — Dentate 

 ovate leaf of the 

 Guelder Rose, with 

 unicostate vena- 

 tion i^Vihurnwii 

 Opulns). 



Fig. 112. ~ Converging 

 veined leaf of ' Cinna- 

 mon. 



Fig. III.— Runcinate leaf 

 of the Dandelion, fea- 

 ther-veined. 



There are also two varieties of the multicostate leaves. In 

 some caseSj as in the Maple (fig. io8), the diverging ribs never 

 meet again. The venation of the leaf is then said to be 

 diverging* or palmate. In other cases, as in the Cinnamon 

 (fig, 112), they meet again at the apex, and the leaf is con- 

 verging veined. 



