Asteraceae

Ambrosia artemisiifolia

Common Names: Annual ragweed

Plant Form: Perennial herb. Size: Up to 2 m tall. Stem: Erect, rounded, hairy. Brownish, greenish, or reddish. Leaves: Bright green to greyish-green. Deeply divided, fern like in appearance. Flowers: Tiny, cup shaped flowerheads, whitish or greenish in clusters of 10-100 along a spike up to 20 cm long. Pollen can give yellowish appearance. Fruit and Seeds: Black or brown seeds with beaked end. Habitat: Waste areas, roadsides, pastures, riparian areas, coastal scrub. Distinguishing Features: Distinguished from lookalike Perennial ragweed (Ambrosia psilostachya) by annual habit and stalked leaves. Distinguished from Parthenium (Parthenium hysterophorus) by having a flower spike.