136 Retrograde Varieties 



finer species of garden-plants, as Sophora jap- 

 onica, have given rise to weeping varieties, and 

 the yew-tree or Taxus has a fastigiate form 

 which is much valued because of its ascending 

 branches and pyramidal habit. So it is with 

 the pyramidal varieties of oaks, elms, the bas- 

 tard-acacia and some others. 



It is generally acknowledged that these forms 

 are to be considered as varieties on the ground 

 of their occurrence in so wide a range of species, 

 and because they always bear the same attrib- 

 utes. The pendulous forms owe their peculiar- 

 ity to a lengthening of the branches and a loss 

 of their habit of growing upwards ; they are too 

 weak to retain a vertical position and the re- 

 sponse to gravity, which is ordinarily the cause 

 of the upright growth, is lacking in them. As 

 far as we know, the cause of this weeping habit 

 is the same in all instances. The fastigiate 

 trees and shrubs are a counterpart of the weep- 

 ing forms. Here the tendency to grow in a 

 horizontal direction is lacking, and with it the 

 bilateral and symmetric structure of the 

 branches has disappeared. In the ordinary 

 yew-tree the upright stem bears its needles 

 equally distributed around its circumference, 

 but on the branches the needles are inserted in 

 two rows, one to the left and one to the right. 

 All the needles turn their upper surfaces up- 



