the acacia is a tree which has many different sub-species, a good number of them living in australia where they are called wattles. the tree i am talking about for this post, however, is a variety native to africa often seen on the savannahs which has a long history. its sticky resin [shown below], is exuded from the trunk and branches of the tree, and collected by workers who are trained to gather it. gum arabic has been used historically as a binding agent for many things and is present in many of the edible items we buy, too.
this product of the acacia can be bought at middle eastern markets and shops and is usually sold in small amounts. note that it is not the same as mastic which looks much the same but is a resin from a different tree [shrub, actually] grown in greece and other mediterranean countries. gum arabic is normally used in a variety of dessert items, such as the recipe i needed it for. the resin acts to emulsify, thicken and flavour some of our foods and drinks. it is in more things than you can imagine. look for it next time in the listing of the ingredients of some of the things you eat. this said, in the resinous form it still remains a specialty item and is not readily available on the shelf at your local supermarket. to be used, it needs to be very finely crushed and pulverized, sifted and then dissolved in a liquid and cooked.
to learn more about this amazing resin, read the fascinating article about its history, production and use, both ancient and modern.