Water-pepper

Water pepper is eaten in Japan, where it is known as tade (蓼), or more specifically, yanagi tade (柳蓼). The leaves are used as a vegetable, but only from the cultivar, not the wild type which has a far more pungent taste. The herb is usually sold in markets as seedlings.[11] Young red sprouts are known as beni-tade (紅蓼), and are used to garnish sashimi, tempura, and sushi. It is popular for summer cooking.[11] The seeds may also be added to wasabi.

Water pepper sauce, known as tade-zu (蓼酢), is a sauce traditionally made from finely chopped water pepper leaves, soaked in vinegar, and a small amount of steamed rice. Occasionally, the juice from a squeezed kabosu is added. In Japanese cuisine it is traditionally used as a complement to grilled freshwater fish, but not saltwater fish.

In China, water pepper is known as la liao (辣蓼), and used in traditional Chinese medicine.

In Indian traditional medicine, leaves of P. hydropiper are used against intestinal helminth infections. A study has proved that P. hydropiper leaves possess noteworthy anthelmintic efficacy and justify their use in traditional medicine against intestinal worms. DOI: 10.1007/s12639-022-01559-2

In Europe, water pepper was once cultivated and eaten during war time as a substitute for pepper.[11]

The plant contains many acids, including formic acid, which makes it unpalatable to livestock.[12] Though mammals do not eat wild water pepper, some insects do, giving rise to the Japanese saying "Tade kuu mushi mo sukizuki" (蓼食う虫も好き好き "Some insects eat water pepper and like it"), which may be translated as "There is no accounting for taste" or "Each to his own."

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