alligator weed

noun

variants or alligator grass

: a prolific herbaceous weed (Alternanthera phylloxeroides) having opposite entire linear-lanceolate leaves and flowers in short headlike spikes and being especially troublesome in irrigation canals and waterways which it clogs with a dense floating mass

Word History

Etymology

so called from its long narrow leaves

First Known Use

1887, in the meaning defined above

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