This aquatic herb is native throughout Southeast Asia, extending into southern China, Japan and Australia. After the Vietnam war, it was brought to North America by refugees, and is now easily available in the Asian markets here in Southern California. This plant grows well in still water, such as found in rice paddies. It's particularly popular in Vietnam, but is also used in China and Japan. In Chinese, Japanese and Korean, the name of this herb is the same as for Perilla, a very distantly related herb. It is made specific with a suffix meaning green leafy plant (see names above).
The flavor is unique, but has been described as a mix of citrus and cumin. It is also used as a medicinal plant throughout its range, and is often grown as an aquarium plant.
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Most popular in Vietnam, this herb is most used in fish soups, especially the famous Sweet Sour Catfish Soup, but also with chicken. It is often present in the raw herb and vegetable platter usually placed in the center of a Vietnamese table, and can be used in salads. In Cambodia this herb is often dried for use out of season.
Buying: A recent purchase at a large Asian market in Los Angeles (San Gabriel) was a 4.8 ounce tray for 2016 US $1.80, or $5.99 / pound.
Storing: This is a rather perishable herb. Wrapped loosely in plastic it will keep a few days in the refrigerator.
Growing: This plant can be easily grown without your needing a rice paddy. Take left over fronds and put them in a deep cup or jar of water. Tent it over with a transparent plastic bag and leave it for a few days to develop roots. You will probably see some roots already at joints. When there are sufficient roots, plant it in a regular pot with a mix of sand and potting soil. Again, keep it tented with clear plastic, with a few small holes in it to allow some air circulation. Keep it in part shade until it is well established. It should need minimal watering. Cut off flower heads when they appear, as it dies after flowering.
Substitute: For soups and the like, the best substitute is a little freshly ground cumin and a bit of lime or lemon zest.