32 BULLETIN 9, U: S. DEPARTMENT OF AGRICULTURE. 
Gum PRopwcts. 
Several species of acacia already naturalized im America yield 
substances of great economic value, although in this country they 
are not as yet commercially utilized. 
One of the most ifiportant of these substances is lac, the product 
of an insect (Zacharia 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,! 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 arabie-—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 anumber 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, Arizona, 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. gummvfera, A. etbarica 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, isin 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, 
1Jn 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. 
