20 



STREET AND HIGHWAY PLANTING. 



years' time, without any special care in planting or afterwards, is no 

 reason why such treatment should be advocated or tolerated. Acacia 

 melanoxylon will stand more water than any other of the acacias and 

 hence is best for parkings where there is grass. Too abundant water 

 supply leads to the production of a superficial root system. Further- 

 more, unless there is special care taken at planting time, this tree will 

 form a surface root system which will not support a tree of any size 

 against heavy winds. 



This acacia grows in many ways. The prevailing type is the pyra- 

 midal one, but there is great individuality among the trees of this 

 shape. Some trees will grow four times as rapidly as their neighbors 

 which have had the same care. By four times as rapidly is meant a 

 growth in height only, as the more slowly growing forms usually make 



a better spread. It has been found 

 necessary and practicable both at 

 Riverside and Los Angeles to do some- 

 thing to make these trees more uni- 

 form. After experimenting it was 

 found that a severe topping, as much 

 as one third at the age of four or 

 five years, made the desired change. 

 There are specimens in the streets of 

 Riverside and in some parts of Los 

 Angeles which have been treated in 

 this fashion very successfully. Those 

 trees which are inclined to be spindly 

 have become broader and have spread 

 out into a good umbrageous head. Of 

 course, discretion must be used in mak- 

 ing this cut, as some trees will not need so heavy a cut as others. In 

 the central and northern parts of the State the irregularity of growth 

 is not so marked and many fine specimens may be found which do not 

 need the severe heading back. 



Acacia retinodes (Plate I, No. 2) is often found on the streets. This 

 is the type to which the horticultural variety Acacia floribunda belongs. 

 It has all the undesirable features of the more common Acacia flori- 

 bunda. "While it is frequently found it is to be urged that its use be 

 discontinued and those now in place relegated to the shrubbery where 

 they belong. That form often offered by the trade as A. floribunda is 

 not a distinct species, but a free growing form of A. retinodes. The 

 variety is a very handsome form of acacia, which is practically ever- 

 blooming. The foliage is attractive and fresh throughout the year, 

 and the new growths which appear nearly the year round bear quanti- 

 ties of fragrant blossoms. 



Figure 2. 



