Absinth Wormwood
Artemisia absinthium L.
Absinth Wormwood is an erect perennial growing up to 4' tall.  The leaves are 1 to 3" long, deeply dissected and covered with fine hair which is gray or silver in color. 

The stems are erect and covered with fine hairs. The flower is small, yellow and found as panicles toward the top of the plant. 

The seeds are formed in the late summer or fall. It has a large, woody tap root.  It's ordor s very distinctive.  European in origin, it has been used for medicinal purposes.
Photos and information adapted from "Weeds of the West" by Tom Whitson