Sagittaria engelmanniana (Engelmann's arrowhead or acid-water arrowhead) is a perennial aquatic plant growing up to 70 centimetres (28 inches) tall. The leaves are sagittate (arrow-shaped) with 3 very narrow lobes.

The species is native to eastern North America. It has been reported from every state bordering on the Gulf of Mexico or on the Atlantic Ocean from Mississippi to Massachusetts, plus Vermont and Ontario. It occurs in wetlands, predominantly those with acidic water such as Sphagnum bogs.