126 



PLANT LIFE. 



There may be a main rib, from whose flanks arise at regular 

 intervals a series of lateral branches which may themselves 



Fig. 148. Fig. 149. 



Fig. 147.— A palmately branched (compound) leaf of horse chestnut. About one-fifth 



natural size.— After Bessey. 

 I'ii.. 148. — A palmately branched (compound) leaf. — After ISessey. 

 FlG. Mi).— Leaflets of maidenhair fern showing dichotomous branching of veinlets, 



which end free. Natural size. — After Ettingshausen. 



again be branched in various ways. Such a leaf is said to be 

 pinnaiely veined (figs. 138, 151, 153). Or (2) from the top 

 of the petiole several large ribs of almost equal strength may 

 be given off. Such venation is palmate (figs. 150, 152). 

 These may be parallel (fig. 150) or radiate (fig. 152). 



The distribution of the small veins or nerves shows three 

 types. They may either (1) connect with each other so as 

 to form an irregular meshed network (fig. 151); or, (2) leav- 

 ing a rib nearly at right angles, they may run parallel with 

 ea< h Other to join another large vein ; or (3) they may leave 



