28 ARRANGEMENT OF LEAVES. 



around the young shoot and always at a very small angle to its long- 

 axis ; their form in connection with that of the cicatrice left by the 

 leaves varies so much in the different genera as to afford a characteristic 

 of each. These outgrowths have sometimes been wrongly described as 

 the " decurrent bases of the leaves." The position taken up by the 

 leaves Avith respect to the axis that bears them is subject to much 

 variation, but in every case with the evident purpose of enabling them 

 to perform their functions to the greatest advantage. On the principal 



Fig. 1& Decussate foliage of Libocednts decu ;/</<>. 



axis or " leader shoot," not only in Abies, Picea, Tsuga, etc., but also in 

 the Araucarias, Sequoia sempervirem, Taxus, Torreya and others, the leaves 

 spread on all sides. This is also the case with side shoots which 

 suddenly quit the horizontal direction and assume an upright position, 

 as is frequently the case in Picea ajanensis, P. sitchensis and others, 

 and normally so in the fastigiate varieties of the common Yew and 

 ( Vphalotaxus. In Ta.<-<><l!iiin <'H4it'lmm and Sequoia semperrirens the 



