1901.] NATURAL SCIENCES OF PHILADELPHIA. 357 



the recurve and the apex. This method of first becoming a little 

 more horizoutal, then recurving near the base and incurving 

 toward the apex is quite common among coniferous trees. The 

 actual bending of the main trunk, which Prof. Bessey and myself 

 ascertained by actual observation in three species of conifera^, may 

 have another illustration in a specimen of the Himalayan Pine, 

 Pimis excelsa, on the estate of Caspar Heft in Germantowu. It is 

 about fifty years old, and probably among the earliest introduced 

 to American gardens. The heavy trunk is curved from near the 

 ground to about twenty feet upwardly. The verticels of branches 

 in this species of Pine extend all around the trunk in a regular 

 horizontal line. In the curved portion of this tree the straight 

 branches on one side are directed above the horizontal line, ou the 

 other side they point below. There can be no other explanation 

 of this than that the tree blew over when about twenty-five feet 

 high, and that the whole of this early twenty-five-year growth had 

 been made to curve. 



Most species of trees will have some of their mature branches 

 incurve or recurve at various ages; and this curving is often char- 

 acteristic of the species. The list is made up from specimens 

 growing on my own property, with the exception of a few left of 

 the original forest, all planted by myself within the past forty 

 years: 



Magnolia. 



In 31. tripetela, M. Fraseri, M. conspicua and M. macrophylla I 

 observe no disposition to curve at any age. But M. acuminata 

 sends out its upper branches at an acute angle, with the apices 

 incurved. After about five years they commence to descend bv 

 a curve near the base. These curves of the lower branches increase 

 in width, until finally the upper portions of the branches again 

 incurve, as noted in many coniferse, especially of the Spruce 

 family. Plate XVI represents a thirty-five-year-old tree. 



Tilia. 



The Lindens : No curving observed in T. Europcea, but in 

 mature trees of T. Americana they are common and striking. 



Ilex. 



I have no large specimens of /. Aquifoliicm. In bushy speci- 

 mens of I. opaea no curving noticed ; but where the plant has 



