1901.] NATURAL SCIEXCES OF PHILADELPHIA. 361 



that most species of Oak, when growing and in nursery rows, pro- 

 duce some weak side branches that soon become horizontal and 

 finally curve. 



Liquidambar. 



The Sweet Gum, Liquidambar styraciflua, seems never to change 

 the angular divergence of its laterals so far as a few inches from 

 the base is concerned, but at a little beyond this they commence to 

 decline at about ten years old in much the same manner as the Pin 

 Oak, but eventually they take an upward bend, so that there is a 

 curving and incurving feature as in the Norway Spruce. 



Fraxinus. 



The Ashes, as a rule, retain their original plan through life, but 

 F, Americana and F. sambucifolia, the 'White Ash and the Black, 

 become very much curved in the older branches. 



Salix. 



In the Willow family I have noted no departures from the original 

 plan; the weeping variety of Salix Japonica, the well-known 

 "Weeping Willow, excepted, as already noted. 



TJlmus. 



There seems to be some tendency in young plants of U. racemosa, 

 the Thomas Elm, to have the weaker brauchlets recurve; but I have 

 no mature specimen. 



Coniferse. 



In the Cypresses, Junipei's and some Pines I have found no evi- 

 dence of the curving of mature branches, but in the Pines, Firs and , 

 Spruces the fact is self-evident. The upper series of about ten 

 years of branching take an acute angle, then a horizontal direc- 

 tion at the base, which is eventually recurved, and finally an 

 incurving occurs toward the younger portion of the branches. In 

 many Pines — Pinus pungens, for instance — when the natural height 

 is about reached, the upper brauchlets become horizontal. The 

 top of the tree is often as flat as if sheared to make a plane sur- 

 face. Judging by pictures of European scenery Pinus Pinea has 

 this habit in the Old World. 



Among monocotyledons, I have noted in the South specimens of 

 Chamcerops Palmetto, that had been evidently turned aside some- 



