Ambrosia psilostachya

Common Names: Western Ragweed

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habit--Ambrosia psilostachya is an herbaceous perennial leaf--this kind of simple leaf is called pinnatifid, because it resembles a pinnately compound leaf

male heads in Fall--these produce massive amounts of windborne pollen (like all ragweeds), and are therefore responsible for many allergies! male heads again--notice how they are pendulous (meaning they hang down)
male heads closeup--here you can see the individual flowers female heads (center)--these occur underneath the male heads on the inflorescence stalks