Ambrosia trifida
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Ambrosia trifida, the giant ragweed, is a species of flowering plant in the family Asteraceae. It is native to North America, where it is widespread in Canada, the United States, and northern Mexico.
Ambrosia trifida
Habit
Inflorescence
Tall specimen in Texas
Noxious weed
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A noxious weed, harmful weed or injurious weed is a weed that has been designated by an agricultural or other governing authority as a plant that is harmful to agricultural or horticultural crops, nat
Ambrosia trifida
…the spike and the latter grow at the end. The fruit is a bur a few millimeters long tipped with several tiny spines. This species is well known as a noxious weed, both in its native range and in areas where it is an introduced and often invasive species. It is naturalized in some areas, and it is recorded as an…
A mature cotton thistle, an invasive weed in Australia
The alga Caulerpa taxifolia is a noxious marine weed nicknamed killer algae. This is a picture of it invading a native plant bed.
This is a parasitic noxious weed, Striga gesnerioides, the cowpea witchweed.
This is a terrestrial noxious weed, Drymaria arenarioides commonly called Lightning weed. It is sometimes confused with daisies.