PALMATE VENATION 



49 



in their course, calibre, branching, &c., they may be re- 

 ferred to as lateral or as basal respectively. Each of 

 them, as also the midrib, usually puts forth secondary ribs 

 arranged pinriately up their sides, and these secondaries 

 bear tertiaries, &c., breaking up into the finer reticula- 

 tion as before. 



a 



f 



Fig. 15. Leaf of Norway Maple, Acer platanoides, showing typical 

 palmate venation, a midrib ; b lateral and d basal primaries ; c secondary 

 rib; e outer branches of primary rib breaking up into secondaries and 

 reticulation (Ett). 



Both in pinnate and in palmate venation the tertiaries 

 from one secondary are apt to run across towards the next 

 ' secondary and meet the tertiaries coming from it, forming 

 w. ii. 4 



