Southwest USA, Mexico
"Volatiles [such as those given off by Mexican Orange leaves] play a significant role in plant–plant, plant–insect and other relationships conveying important messages that usually require minute quantities of volatile secondary metabolites that are part of an inhomogeneous group of compounds (commonly jointly termed as essential oils). Many plants emit volatiles to attract pollinators or repel herbivores, especially useful at night when visual clues become insufficient. Essential oil constituents can be biosynthesized by several pathways, wherein benzenoids, isoprenoids and fatty acid derivatives are their most typical chemical classes." 
"In 1923, Standley reported that Mexican people employed infusion of leaves for their antispasmodic and “simulative properties”; Choisya ternata was registered in the 4th and 5th edition of the Mexican Pharmacopoeia. As far as we know, the present use of Choisya ternata is not widespread." 
"Natural substances derived from plants have played an extremely important role in the development of analgesic drugs and in the understanding of the complex mechanisms involved in pain transmission and pain relief. For example, salicin, a glycoside obtained from the bark of Salix species, was the lead compound for the synthesis of aspirin based on its activity and structural properties. Recently discovered antinociceptive substances include alkaloids, terpenoids and flavonoids. Such findings have opened new possibilities for research into new potent analgesic drugs based on structure–activity relationships." 
 Radulović, N. S., Miltojević, A. B., McDermott, M., Waldren, S., Parnell, J. A., Pinheiro, M. M. G., ... & de Sousa Menezes, F. (2011). Identification of a new antinociceptive alkaloid isopropyl N-methylanthranilate from the essential oil of Choisya ternata Kunth. Journal of ethnopharmacology, 135(3), 610-619.