TYPES OF LEAVES 



49 



attached along the margin of the petioles as in the clovers; 

 sometimes they are developed as sheaths enclosing the stem as 

 in the grasses and grains ; and sometimes' they enclose the young 

 leaves as in the tulip tree. 



Types of Leaves. Leaves which have one prominent mid- 



Fio. 36. Palmately veined leaf. 



Fia. 37. Palmately veined leaf. 



rib running from base to apex, and giving rise to numerous side 

 branches with smaller veinations between them are said to be 

 net-veined (Fig. 34), while leaves which have a number of 

 equally prominent veins running from base to tip are said to 

 be parallel-veined. (Fig. 35.) Most dicotyledonous plants 

 have net-veined leaves, while most monocotyledonous plants 

 have parallel-veined leaves. Leaves which have three, five or 

 more prominent ribs or veins arising from a common point are 

 said to be palmate-net-veined or radiate-net-veined (Figs. 36 

 and 37), while those that have numerous veins arising from a 

 main mid-rib are said to be pinnate-net-veined or feather-net- 

 veined. (Fig. 34.) 



