V] SIMPLE AND PINNATE VENATION 55 



This may be termed simple venation, and when entirely 

 hidden in the substance of the leaf we may term it obscure 

 or obsolete. Examples are afforded by the following. 



The venation is simple or obsolete, consisting of one rib 

 (though there may be invisible cross-ties) or vein only, in 

 Tamarisk Pines Spruces 



Firs Larch Cedars 



Juniper Yew Cypresses 



Thuja Heather Ling, 



and it is more or less simple or obscure in the small 

 leaves of 



Broom Mistletoe Gorse 



Sea Buckthorn Petty Whin Myrica. 



The next case shows a single primary rib, the midrib, 

 running from base to apex of the leaf or leaflet, and this 

 gives off secondaries to right and left in pinnate order. 

 These are straight, or nearly so, and run direct to the 

 margin and end there, either without branching or putting 

 forth fork-like branches all of which end direct in the 

 margin ; or they may again fork and the forks end there. 

 In those cases where the secondaries run merely towards 

 or near the margin, with no marked parallelism or straight- 

 ness of course, the term pinnate, simply, may be applied ; 

 but in cases where the course of the secondaries is stiff 

 and straight right up to the margin, and parallel one with 

 another, we may conveniently use the term strict-pinnate. 

 Viburnum Lantana (Fig. 14) affords a typical example of 

 the former; and the Chestnut (Fig. 16) one of the latter. 



The following also afford examples of pinnate vena- 

 tion : 



Laburnum Blackberry Raspberry 



Rowan Service Tree Virginian Creeper 



Aucuba Wa\ faring Tree Box 



