Limnophila aromatica

Limnophila aromatica (synonym: Limnophila chinensis var. aromatica; also called rice paddy herb) is a tropical flowering plant in the plantain family, Plantaginaceae. It is native to Southeast Asia, where it flourishes in hot temperatures and grows most often in watery environments, particularly in flooded rice fields. It is used in Vietnamese cuisine and also cultivated for use as an aquarium plant. The plant was introduced to North America in the 1970s due to Vietnamese immigration following the Vietnam War.

L. aromatica was formerly classified as a member of the figwort family, Scrophulariaceae. L. aromaticoides is actually not a distinct species, but a variety of L. aromatica.

Culinary use
L. aromatica has a flavor and aroma reminiscent of both lemon and cumin. It is used most often in Vietnamese cuisine, where it is called ngò ôm. It is an ingredient in canh chua, a sweet and sour seafood soup which also includes tamarind, and is sometimes also added as an accompaniment to the noodle soup called phở.