Definition of horseweed
1 : a common annual American composite herb (Conyza canadensis synonym Erigeron canadensis) with an erect usually hairy stem and small discoid heads of yellow disk flowers
2 : a coarse annual North American ragweed (Ambrosia trifida)
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Recent Examples of horseweed from the Web
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Yet tolerance to 2,4-D has already been documented in several weed species that have elsewhere become glyphosate-resistant superweeds, including waterhemp and horseweed.
These example sentences are selected automatically from various online news sources to reflect current usage of the word 'horseweed'. Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.
First Known Use of horseweed
1790
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