sweet flag

noun

variants or less commonly sweetflag

ˈswēt-ˈflag 

or sweet-flag

plural sweet flags also sweetflags or sweet-flags

: any of a genus (Acorus of the family Acoraceae) of perennial herbaceous plants that are typically found in wetlands of the northern hemisphere and have long narrow leaves and aromatic roots

Here, the bright chartreuse blades of grassy-leaved sweet flag grow in front of big, bold … hosta …

—Inta Krombolz

The water reflects the trees and sky; the palette is a range of greens—grass, conifers, green-and-white sweet flag.

—Eleanor Dwight

especially : an Asian plant (Acorus calamus) that has been introduced to Europe and North America that has been used especially formerly as a flavoring agent and in alternative medicine but is now banned for these uses in several countries because of its potential carcinogenic effects and toxicity : calamus

Sweet flag is poisonous under certain conditions causing disturbed digestion, gastroenteritis, persistent constipation, … and passage of blood into the feces. In 1968 the U.S. Food and Drug Administration reported that the use of sweet flag was unsafe. The report was issued due to cancerous tumors found in lab animals treated with the plant.

—Timothy J. Motley

Meanwhile, the Mexican government has banned the use of some species of plants in infusions or vegetable oils because of the level of toxicity. … The latest list, from 1999, prohibits 76 species, including some that are habitually used by herbalists and traditional medicine practitioners, such as calamus or sweet flag … belladonna, wormseed, rue and salvia.

—Emilio Godoy

Examples of sweet flag in a Sentence

Recent Examples on the Web

Marginal plants such as purple pickerel rush, sweet flag, and variegated water celery (Oenanthe javanica) grow in shallow water along the pond’s edges. —Miranda Crowell, Better Homes & Gardens, 29 May 2025

Word History

First Known Use

1765, in the meaning defined above

Rhymes for sweet flag

• airbag
• handbag
• ragtag
• sandbag
• ag
• bag
• brag
• dag
• drag
• gag
• hag
• hagg

Medical Definition

sweet flag

noun

-ˈflag 

variants also sweetflag or sweet-flag

: any of a genus (Acorus of the family Acoraceae) of perennial marsh herbs with long leaves and a pungent rootstock

especially : a perennial marsh herb (Acorus calamus) native to Asia but introduced to Europe and North America that was used especially formerly as a flavoring agent and in alternative medicine but is now banned for these uses in several countries because of demonstrated carcinogenicity and toxicity in laboratory animals : calamus sense 1