ARBORICULTURE 



ARBORICULTURE 



381 



Acacia pycnantha. 

 Eucalyptus amygdalina. 

 Eucalyptus Gunnii. 

 Eucalyptus leueoxlyon. 

 Eucalyptus obliqua. 

 Eucalyptus rostrata. 

 Eucalyptus rudis. 

 Eucalyptus viminali>. 



cc. Hardy. 



Jubsea spectabilis. 

 Phoenix canarie^i--*. 

 Phoenix reclinata. 

 Phoenix sylvestris. 

 Pittosporum eugenioides, 

 Pittosporum tenuifolium. 

 Pittosporum undulatum. 



Acer saccharinum 

 laciniatum. 



Betula pendula elegans, 



Betula pendula laciniata. 



Betula pendula Youngii. 



Cratsegus monogyna var. pen- 

 dula. 



Fagus sylvatica yar. pendula, 



Fraxinu* excelsior var. aurea 

 pendula. 



Fraxinus excelsior var. pen- 

 dula. 



Morus alba (Teas' weeping). 



Drooping trees. 

 B. Deciduous. 



Wieri 



Populus grandidentata var. 



pendula. 

 Prunus fructicosa var. pendula. 

 Quercus lobata. 

 Satix babylonica. 

 Salix babylonica var. Lickii. 

 Sophora japonica var. pendula. 

 Sorbus Aucuparia var. pendula. 

 Tilia americana var. pendula. 

 Tilia europsra var. pendula. 

 Ulmus americana var. pendula. 

 Ulmus campestris var. pendula. 

 Ulmus scabra var. pendula. 



Cupressus funebris. 

 Cupressus lusitanica. 



BB. Evergreen. 



Schinua Molle. 



6. Trees for streets, avenues and roadsides in California. 



The number of tree species suitable for street plant- 

 ing is limited by the necessarily heavy restrictions, as to 

 height, spread, sewer-penetra- 

 tion and sidewalk-raising, im- 

 posed by municipal street de- 

 partments. In European cities 

 the first-named objections are 

 overcome by means of frequent 

 and systematic pruning to a 

 uniform standard: when this 

 necessity can be obviated by 

 the selection of trees which 

 naturally keep within the de- 

 sired bounds, the labor of 

 maintaining them in a sightly 

 condition is minimized and the 

 result much more pleasing. 



For town streets not more 

 than 60 feet in width, it is im- 

 portant to have trees that will 

 not give too much shade and 

 prevent the rapid drying of 

 the roadway after showers, nor 

 be so tall nor wide-spreading 

 as to obstruct the view and 

 shut out sunshine, rendering 

 the adjacent houses dark, cold 

 and damp. On this account, 

 trees with narrow or pyramidal 

 outline are in many cases pref- 

 erable to those "with wide- 

 spreading habit, and, generally 

 speaking, deciduous trees are 

 more suitable than evergreen, 

 although at the time of losing 

 their leaves they make more 

 litter. Exception may be made 

 in favor of such evergreen spe- 

 cies as certain palms and eordylines, some acacias and 

 a few other species mentioned below. 



It is not wise to use trees of very rapid growth on 

 town streets: they soon become too large and require 

 frequent trimming, which is usually equivalent to 

 mutilation, and are likely to interfere with sewers. 



It cannot be said that street planting in California 

 towns has. in most cases, been satisfactory. In spite of 

 the much larger variety of suitable material than is 

 available in most of the states, there are few examples 

 of good street planting to be met with. In most of the 



359. Cordyline australis or "dracena palm." 

 Common in California. 



towns the eye is greeted with a few straggling trees, of 

 which perhaps not more than two are of one kind, 

 recalling F. A. Waugh's apt simile of "nine mon- 

 strously different buttons in a row down the front of a 

 Prince Albert coat." There are many pleasing excep- 

 tions, however, although few are entirely satisfactory. 

 The repeated attempts to improve the appearance of a 

 town by planting trees along the streets should be 

 encouraged on every occasion, and the object of this 

 discussion is to render assistance by pointing out how 

 some of the mistakes may be avoided. The unsatis- 

 factory results of street planting, so often met with, 

 can generally be traced to one or all of three causes: 



(1) Choice of unsuitable species. 



(2) The mnring of several species on the same block 

 and even in front of the same lot. 



(3) Crowding of trees. 



This last-mentioned source of trouble is perhaps the 

 cause of more failures than the first. When trees are 

 once growing, few persons have the heart to thin out 

 the species for the proper distance apart; finally, a new- 

 comer, without personal feeling in the matter and noting 

 only that there is too much shade and too little light, 

 cute down the whole row and a gap is left in what may 

 have been a fairly uniform block. Spreading avenue 

 trees of large size should not stand closer than 50 feet 

 apart ; smaller trees, on narrower streets, should have 40 

 feet, unless they are slender species such as cordyline 

 or washingtonias, when 20 feet may be sufficient. As a 

 rule, one small tree to a 50-foot 

 lot will be found ample; if the 

 whole street is planted uni- 

 formly with the same species, 

 and at this same distance, the 

 result will be much more pleas- 

 ing than if four or five trees are 

 planted in front of every house. 

 This question of spacing can 

 be determined only by the 

 species in use. If 20 feet is 

 added to the diameter of the 

 spread of the crown, an approxi- 

 mate spacing can be secured. 

 For example, cork elms often at- 

 tain a 60- or 75-foot spread and 

 should be spaced, accordingly, 

 80 to 100 feet apart. This ad- 

 vice is given from data gathered 

 in various towns where closer 

 plantings were in order, and 

 have already demonstrated how 

 the air, light and heat are shut 

 off by too crowded plantings. 



In towns where the climate 

 is very mild, with few extremes, 

 trees are planted only for dec- 

 orative effect and not for 

 shade, hence these extreme 

 distances may be used even for 

 species which do not attain 

 great size. 



On the other extreme in the 

 interior California valleys, the 

 distances may have to be short- 

 ened to allow for the extreme 

 heat, but trees should never be set so closely that the 

 circulation of air is hindered, except of course for wind- 

 break plantings, which are not found on streets as a rule. 



A. For city and totcn streets. 

 B. Small trees suitable for streets 60 feet wide or less. 



c. Deciduous. 

 D. Growth rapid or moderate. 



.Esculus carnea. 

 Betula alba. 

 Betula lutea. 



Betula populifolia. 

 Catalpa bignonioide 

 Catalpa ovata. 



Catalpa speciosa. 

 Koelreuteria paniculata. 

 Paulownia tomentoaa. 



