About Limnophila aromatica (Lam.) Merr.
Limnophila aromatica, commonly known as rice paddy herb, is a tropical flowering plant belonging to the family Plantaginaceae. It is native to Southeast Asia, where it thrives in hot temperatures and most commonly grows in watery environments, particularly flooded rice fields. In Vietnam, it is known as ngò ôm, ngò om, or ngổ, where it is used as a culinary herb and also cultivated to be grown as an aquarium plant. This species was introduced to North America in the 1970s, brought over by Vietnamese immigrants following the Vietnam War. In Khmer, the plant is called ma om (ម្អម). It is used in traditional Cambodian soup dishes and Southern Vietnamese cuisine. While it can grow in flooded rice paddies during the wet season, it grows best on drained but still wet sandy soil of harvested rice paddies for several months after the rainy season ends. It dies out soon after flowering. Rural Cambodians often harvest the plants and dry them on the roofs of their houses for later use. Limnophila aromatica has a flavor and aroma that are reminiscent of both lemon and cumin. It is used most often in Vietnamese cuisine, where it goes by the name ngò om. It is an ingredient in canh chua, a sweet and sour seafood soup that also includes tamarind, and should not be confused with ngò gai, which is added as an accompaniment to the noodle soup phở. In Thai cuisine it is known as phak khaeyng (ผักแขยง), and is also used to make om. Limnophila aromatica can grow completely submerged, making it a popular aquarium plant. Submerged leaves are larger and less rigid than emergent leaves; they are green with a purple underside, and turn fully red when grown under high light conditions.
