86 JOURNAL OF THE ARNOLD ARBORETUM (vol. iv 



and also in the South Island of New Zealand. In the latter country P. 

 alba var. pyramidalis Bge. (P. Bolleana Lauche) does very well and ought 

 to be given a good trial in South Africa, and so, too, should the Carolina 

 Poplar of American nurseries, a supposed hybrid between P. balsamifera 

 L. and the Lombardy Poplar and named P. canadensis var. Eugenei 

 Schelle. The Lombardy Poplar (P. nigra var. italica Dur.) is, of course, 

 planted in many places and thrives in not a few but its use is mainly as 

 a wind-break. The White Poplar (P. alba L.) from some reason or other 

 appears to be rare, at least in the parts of the southern hemisphere visited 

 by me. There is little hope of the Aspens (P. tremula L. and P. tremuloides 

 Michx.) being successfully grown, much less naturalized, in the antipodes 

 except possibly on the mountains in southern New Zealand. The north 

 China P. tomentosa Carr. is a species worthy of trial in South Africa and 

 New Zealand and one would think that the species from the dry sunny 

 regions of southwestern North America were worth experimenting with 

 especially in South Africa. For example such species as P. arizonica 

 Sarg., P. texana Sarg., P. Fremontii S. Wats, and P. McDougallii Rose 

 ought certainly to be given a good trial. 



What I have written does not pretend to exhaust the list of Soft and 

 Hardwood northern trees introduced into Australasia and South Africa 

 though no tree of proved importance has been omitted. If the home of 

 these trees be inquired into it will be seen that it is the trees of western 

 North America from central California southward including Mexico, those 

 of vhe Mediterranean region including the Levant and those of the north- 

 west Himalayas that grow best in the southern lands under review. The 

 trees of China and Japan, with the exception of the Babylon Willow (Salix 

 babylonica L.) and the Camphor-tree (Cinnamomum Camphora Nees & 

 Eberm.), those of northern Europe, except the Larch (Larix decidua Mill.) 

 and White Willow (S. alba L.) in New Zealand and Quercus robur L. at 

 the Cape of Good Hope, and those of eastern North America, except the 

 Tulip-tree (Liriodendron Tulipifera L.) and Sweet Gum {Liquidambar 

 Styraciftua L.), grow badly and give little promise of success. The trees 

 of southeastern United States, especially certain species of Pinus, ought 

 to be given a fuller trial, for very possibly they like their fellow countrymen, 

 the Swamp Cypress (Taxodium distichum Rich.) and the Bull Bay 

 (Magnolia grandiflora L.), will be found to thrive where climate, soil and 

 rainfall are favorable. It is only by experimental planting that the value 

 of any tree can be determined. As far as my observations go and granted 

 that the minimum temperature is not too low, the only point of practical 

 importance to be kept in view in the planting of exotic trees is that of the 

 season of rainfall. In lands of marked wet and dry seasons it does make 



an enormous difference in the behavior of tree-growth whether the wet 

 season is that of winter or of summer. Where rainfall is sufficient the 

 chemical properties of soils appear to be of much less importance than 

 their physical character. As proof of this I may instance Pinus radiata 1). 



