186 TREES 



grown in open ground, and known as "tassel trees," attain 

 good size. 



Valuable lumber, tanbarks, dyes, perfumes, and drugs 

 are yielded by acacias. Gum Arabic is the dried sap of 

 several oriental species, particularly. Acacia Arabica, Linn, 

 of Egypt and southern Asia. 



As a rule, acacias have slender branches armed with 

 spines. Often these are too small to attract notice, or to 

 make the species useful as a hedge plant. All spines are 

 modifications of the stipules at the base of leaf or leaflet. 

 Thorns, however, are modified twigs, strong, stiff and 

 sharp, often branched. The honey locust shows true 

 thorns, not spines or prickles. The armament of canes of 

 blackberry is only skin deep. This means of defence is 

 best called "prickles." 



The Black Acacia 



Acacia melanoxylon 



The black acacia, called at home in Australian woods, the 

 "black wood-tree," for its black heart- wood, is a familiar 

 street and shade tree in California. In narrow parkings it 

 is likely to surprise the planter by outgrowing in a few 

 years the space allotted to it, and upheaving both cement 

 walk and curb, by the irresistible force of its thick roots. 

 It is one of the large timber acacias, and even in the cool 

 climate of England reaches fifty feet. 



In suitable situations in California it grows much higher, 

 and its compact conical head of dense evergreen foliage, 

 gives abundant shade at all seasons. The flowers are 

 white or cream-colored, lightening the yellow-green of the 



