Life (root) » Plantae (plants) » Tracheophyta (Vascular Plants) » Angiospermae (Flowering Plants) » Magnoliopsida (Dicots) » Asterales (asters, bellflowers, fanflowers, and allies) » Asteraceae (sunflowers, daisies, asters, and allies) » Asteroideae » Heliantheae (sunflowers and allies) » Ambrosiinae » Ambrosia (ragweeds) » Ambrosia psilostachya (western ragweed)