Ragweed Parthenium

Ragweed Parthenium

Parthenium hysterophorus L.

Asteraceae (Aster Family)

▲ seedling

▲ ▼ flowering plants

▲ flowers

Ragweed Parthenium:

annual growing 12-48" tall with dark-gray-green divided leaves and small white flowers
leaves look like common ragweed leaves
inflorescences form rounded to flat-topped, open cluster at top of plant
produces abundant pollen that can aggravate allergies in allergic individuals
found in dry to moderately moist soils of various fertility
has shown herbicide resistance and invasive nature in other countries
occasional weed in southwest Missouri (not common)