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water mint

British  

noun

  1. a Eurasian mint plant, Mentha aquatica, of marshy places, having scented leaves and whorls of small flowers

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Example Sentences

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Other plants to have colonised the site include common reed, greater pond sedge, celery-leaved buttercup, marsh valerian, purple and yellow loostrife, yellow flag iris, fen bedstraw and water mint.

From BBC

But those which perfume the air most delightfully, not passed by as the rest, but being trodden upon and crushed, are three, that is burner, wild thyme, and water mints.

From Project Gutenberg