With the decline of citrus trees in back yards, the giant swallowtail butterfly (Papilio cresphontes) could be in jeopardy, as it relies on citrus trees to lay its eggs on. Fortunately, any member of the citrus family (Rutaceae) will suffice. One such member is the native wild lime tree (Zanthoxylum fagara). It looks more like a very large shrub than a tree, and it does not bear edible fruit. In fact, the fruit is so small, you would be hard pressed to even see it on the tree. It is rather thorny and dense, which makes it an excellent natural barrier to keep people and unwanted pets from entering or leaving your yard. More importantly, it is an excellent host plant for the afore mentioned Giant Swallowtail Butterfly.
Richard Lyons Nursery currently has this plant in stock.