66 



MANUAL OP BOTANY 



either as a single main vein, or several similar ones, breaks up 

 into a network of branches (yZj'g. 108 and 110). In the second 

 modification, a midrib runs from the base to the apex of the 

 lamina, giving off from its sides other veins, which go out to 

 the margins, running parallel to each other, and are simply 

 connected by unbranched veinlets {figs. Ill, 6, and 118) ; 

 or it divides at once into several veins or ribs, which proceed 

 from the base to the apex {fig. 116), or margins {fig. 117) of 

 the blade, more or less parallel to one another, and are in 

 like manner connected only by simple parallel unbranched 



Fie. 112. 



Fig. 113. 



Fig. 114. 



Fig. 115. 



Fig, 112. Feather- veined leaf of the Spanish Chestnut. Fig. 113. Feather- 

 veined leaf of the Oak. Its lobes are arranged in a pinnatifid manner. 



Fig. 114. Leaf of the Dead-nettle. The venation is the true-netted, and its 



margins are serrate. Fig. 115. a. Linear leaf. 6. Triple-ribbed leaf of 



the common Suuiiower. 



veinlets {fi^. Ill, a). The leaves which exhibit the first modi- 

 fication of venation are called reticulated or netted-veined 

 leaves, and occur universally in Dicotyledons ; and those which 

 present the second modification are termed paralhl-veined 

 leaves, and are characteristic, with some few exceptions, of 

 Monocotyledons. 



(1) Varieties of Beticulated or Netted Venation. 



There are two principal varieties of this kind of venation, 

 namely, the feather-veined or pinnately veined, and the radiated 

 or iialmately veined. 



