The state of Nevada encompasses six "life zones"; Alpine, Sub-alpine, Yellow Pine, Pinion-Juniper, Sagebrush and Creosote. As US95 rises towards Tonopah with the Goldfield Summit receding behind you, you'll cross a noticeable boundary between zones. Creosote bushes (Corvillea Tridentata, a variation of Larrea Tridentata) give way to sagebrush (Artemisia Tridentata). This is a very sharp boundary lasting less that 1/4 mile. Beyond that point, you won't see any flora which was firmly established only a mile back.