While visiting the Arizona Historical Society Museum at Papago Park (1300 N. College Ave, Tempe Arizona 85281) I saw fossil specimen (AHS-NH#13056) from Navajo County, Arizona USA. It is petrified wood. This plant existed in the Upper or Late Triassic Period. There are some really beautiful colors in this piece. The display is located right in the front entrance lobby as of October 2014.
