Ever notice the smell that is given off by creosote bushes when it rains? It's caused by a resin which coats the leaves of the plant. The resin protects it from water loss.
Although some refer to the odor of the crushed leaves as the “heavenly essence of the desert,” the Spanish word for the plant, hediondilla, means "little stinker," signifying that not everyone considers the odor heavenly or pleasing to the senses.
LINK: http://phoenix.about.com/cs/desert/a/creosote.htm