﻿32 BULLETIN 9, U. S. DEPARTMENT OP AGRICULTURE. 



Gum Products. 



Several species of acacia already naturalized in America yield 

 substances of great economic value, although in this country they 

 are not as yet commercially utilized. 



One of the most important of these substances is lac, the product 

 of an insect ( Tacharia lacca) of the coccid family, which feeds on 

 the juices of many host plants and especially on certain acacias. 

 Lac culture is a large and profitable industry in several countries 

 and there is an increasing demand for the product. The literature 

 of the industry is voluminous, particularly in the forest publica- 

 tions of the Government of India, 1 where Acacia catechu and A. arabica 

 are cultivated as hosts for the lac insect. Acacia farnesiana, per- 

 haps more valuable for perfumes, is also a lac-yielding species, as is 

 the American Acacia greggi of Arizona. Since the value, of the lac 

 product on various species differs greatly, there is room for wide 

 experimentation with those grown in America; it is generally consid- 

 ered, however, that Acacia catechu, the "kair tree" of India, is one 

 of the best. 



Gum arabic. — Any mention of vegetable gums immediately brings 

 to mind the widely known gum arabic, derived from Acacia arabica 

 as the type, but yielded also by a number of Asiatic and African desert 

 species, all of which thrive in the warmer parts of the United States, 

 and growing where the date palm has been successfully introduced, 

 but requiring much less moisture. They are strongly alkali resistant 

 and are adapted to true desert conditions. They should prove of 

 value, therefore, in southern California, j^rizona, and New Mexico. 

 The more valuable gums used in medicine and in various arts and 

 industries come from the Acacia arabica, A. Senegal, A. suma, A. verek, 

 A. farnesiana, A. stenocarpa, A. gummifera, A. etbaica and others. 

 The yield is variously graded and is marked under several trade 

 names. Single trees will flow each year from a few ounces to a few 

 pounds of gum, and the bleeding process can be continued for many 

 years without harm to the plant. 



Many other gums are yielded by acacias, some of them highly 

 astringent. Cutch, a product of Acacia catechu, is in constant demand 

 and reaches market in several forms, as crystals found in the wood 

 and as a gum, both pale and dark. 



The cheaper grades of gum are yielded mainly by the Australian 

 acacias and are in general use. All of the decurrens varieties of 

 tanbark acacias yield commercial gums in large quantities, known 

 specifically as wattle gums and used as a size for leather, as a sub- 

 stitute for isinglass, and for many other industrial purposes. Acacia 

 binervata, A. pendula, A. glaucescens, A. retinoides, A. homalophylla, 



1 In this connection there is a suggestive paper on the propagation and collection of lac contributed by 

 Mr. Lowrie, deputy forest conservator, to the Nagpur Forest Conference of 1908. 



