THE LEAF 3^ 



CuRVl-VElNED. In pinni-veined leaves (see fig. 28) 

 the blade is traversed by a long thick central vein 

 called the mid-rib, which divides the blade into two 

 equal halves, and is the continuation of the petiole. 

 From the mid-rib on either side of it a number of 

 thinner secondary veins are given off, which proceed 

 towards and terminate near the margins. These 

 secondary veins are like the feathers or pinnae of a 

 quill, and hence the venation has been styled pinni- 

 or feather- veined. When the mid-rib divides the 

 blade into two unequal parts, the leaf is said to be 

 UNEQUAL or unsymmetrical, as in Begonia. Unequal 

 leaves are not very common. 



In palmi-veined leaves (see fig. 167) there is not 

 one principal or central mid-rib continuous with the 

 petiole, but a number of stout ribs radiate from the 

 base of the blade towards its margin, as if the petiole 

 had split up into so many branches on entering the 

 blade. The radiating veins look like the outstretched 

 fingers of the human palm, from which resemblance 

 the name palmi-veined originates. In parallel-veined 

 leaves (see fig. 22) the blade is traversed by a num- 

 ber of veins nearly parallel to the mid-rib. Sometimes 

 these veins are more or less curved, then the leaf is 

 said to be curvi-veined (see fig. 24). The majority 

 of Monocotyledons are parallel-veined, whereas the 

 majority of Dicotyledons are pinni-veined or palmi- 

 veined, Curvi-veined leaves are comparatively few, 

 as tezpat {Cinnamomuin Tamala), dalchini {Cinna- 

 momum zeylamcum), kappur (Cinnamomum Cam- 

 phora), kul or baer {Zizyphus Jujuba), kuchila 

 {Strychnos Nux-vomica), nirmalli or Clearing-nut 

 \Strychnos potatorum), Osbeckia, Melastoma, Dios- 

 corea (see fig 190; Plate IV, fig. A; and fig. 24). 



In Dicotyledons the principal veins, as a rule, 



