About Ambrosia chamissonis (Less.) Greene
Ambrosia chamissonis is a large, sprawling perennial herb that reaches a maximum width of over 3 meters (9.8 feet). Its stems are covered in coarse or soft hairs and bear longitudinal ridges. It produces numerous leaves that are a few centimeters long, woolly in texture, silver-green in color, and vary in shape. This species is monoecious, meaning each individual plant bears both male and female flowers. Staminate (male) flower heads, which hold many pale-colored florets, grow at the tip of the inflorescence, while pistillate (female) flower heads are clustered just below them. Each pistillate flower head contains a single tiny flower that develops into a fruit. The fruit is a brown bur up to 1 centimeter wide, covered in sharp spines.
