Volatile Compositions of Two Cactus Species Growing in the Sonoran Desert of Southern Arizona

Abstract

The essential oils of Opuntia acanthocarpa var. major and Opuntia phaeacantha var. discata (Cactaceae) growing wild in the Organ Pipe Cactus National Monument, Ajo, Arizona, and the Arizona-Sonora Desert Museum, Tucson, Arizona, were obtained by hydrodistillation and analyzed by gas chromatography – mass spectrometry. The volatile oil yields and compositions of each cactus species growing in the two locations were significantly different. The differences may be attributed to rainfall differences as well as differences in soil composition between the two sites. Organ Pipe Cactus National Monument is a drier habitat than the Arizona-Sonora Desert museum. The soil of the Organ Pipe Cactus National Monument is rich with lime while soil at the Arizona-Sonoran Desert Museum is dominated by caliche. O. acanthocarpa var. major and O. phaeacantha var. discata growing in the drier, limey soil of the Organ Pipe Cactus National Monument had essential oils dominated by alkane hydrocarbons, while O. acanthocarpa var. major from the Arizona-Sonora Desert Museum was rich in chromenes, and p-vinylguaiacol dominated the composition of O. phaeacantha var. discata growing in the caliche-rich soil of the Arizona-Sonora Desert Museum.