Water Pepper (Persicaria hydropiper [L.] Spach)

In Japanese cooking, the fresh leaves are used. The dried seeds have a strong pungency, but I have not heard of them being used in any ethnic cuisine.

Polygon­aceae (buckwheat family)

The plant has hardly any odour. On chewing, it is slightly bitter in the first moment, but then develops a pungent, biting–prickling heat, which lasts for a while, similar to Sichuan pepper.

See also negro pepper about pungent and zedoary about bitter spices.

Water pepper (sterile twig)

A bicyclic sesqui­terpenoid, polygodial (tadeonal, an un­saturated dialdehyd with a drimane backbone) has been found responsible for the pungent taste; rutin (see rue) is the source of the bitter taste impression. Polygodial also appears in an exotic Australian spice, Tasmanian pepper, and, in small quantity, in the Brazil paracress.

The plant contains an essential oil (0.5%) which is mainly made up of monoterpenoids and sesquiterpenoids: α-pinene, β-pinene, 1,4-cineol, fenchone and α-humulene, β-caryophyllene, trans-β-bergamotene. Carboxylic acids (cinnamic, valeric, capronic acid) and their esters were present in traces. The composition depends strongly on genetic factors.

The plant grows at wet places in temperate to tropical Eurasia, North Africa and North America. The subspecies from temperate climate (ssp. hydropiper) is larger and has two-sided fruits, whereas the tropical subspecies (ssp. microcarpum) is generally smaller and produces three-sided fruits.

Water pepper twig bearing flowers

Water pepper flower

The term water pepper is motivated on one hand by the pungent peppery taste and on the other side by the plant’s natural habitat; analog formations are found in other European languages (German Wasser­pfeffer, French poivre d’eau, Serbian vodeni biber [водени бибер] or Russian perets vodyanoj [перец водыной]). Cf. also the English term marsh pepper and the Romanian name piper broaștei (piper broaştei) frog’s pepper.

The botanical species name, hydropiper, derives directly from the classical Greek plant name hydropeperi [ὑδροπέπερι], which appears in Dioskurides’ medical plant book (hydor [ὕδορ] water and peperi [πέπερι] pepper).

The word water has relatives in nearly every Indo–European language: Hittitee wātar [𒉿𒀀𒋫𒅈], Greek hydor [ὕδορ], Russian voda [вода] (vodka [водка] is a diminutive little water), Irish uisce (whisky is shortened from Gaelic uisge beatha water of life), Lithuanian vanduo, Sanskrit uda [उद] water, furthermore Latin unda wave. Another related English words are otter and possibly aurochs. At these words’ basis lies a variable Proto-Indo–European root WED- with basic meaning wet, whence WODR̥ water is derived.

Water pepper

The Latin word for water, aqua, lives today in the Romance languages, e. g., in Italian acqua and French eau. In Germanic tongues, we have Gothic ahva, Old High German aha, Old English ea and Old Norse a water, Modern German Au area around a river. Possibly related words are found in other Western Indo–European tongues: Hittitee ekuzi he drinks and Tocharic yok- drink, which might all derive from Proto-Indo–European­pean AKʷĀ water.

About the genus name Poly­gonum, see the closely related Vietnamese coriander.

Sorting Persicaria names (www.plantnames.unimelb.edu.au)