CH. VI l] YEW BUDS. 197 



developing buds, but when the internodal twist has taken 

 place in a complete manner (which is not always the case) 

 the decussation disappears, and the leaves seem to be 

 arranged in two instead of four ranks. 



<226) The buds of the yew (Taxus). 



In the young leaf-bud of the yew it will be seen that 

 the morphologically upper surfaces of all the leaves are 

 directed towards the centre. Since the shoot grows 

 horizontally it is clear that the leaves growing on its 

 upper surface must twist on their petioles in order that 

 their upper surface may face upwards 1 . If a yew branch 

 bearing quite young buds is fixed in a horizontal position 

 with its lower surface upwards, the twisting of the leaves 

 takes place precisely as it does in a normal branch. Thus 

 the shoot, although in the arrangement of its leaves it 

 resembles a normal shoot, really developes with its 

 morphologically upper side downwards. In this respect 

 it differs from the shoots of the hazel, lime, etc. in which 

 an inverted shoot recovers its normal position by means 

 of torsion of the internodes. The best way of fixing 

 the yew branch in its inverted position is not to twist 

 it on its axis but to bend over a horizontal branch 

 into a C form, until its free end is inverted but hori- 

 zontal; it can be fixed in this position by being tied in 

 two places to a stick fixed into the earth. The torsion 

 of the leaves requires several weeks for completion. 



1 See a good figure of Abies pcctinata iii Frank's Lehrbuch der 

 Botanik, 1892, i. p. 475. 



