Water pepper : Smartweed.

Water pepper : Waterwort.

Example:


Taxonomy
Water-pepper, free encyclopedia, Persicaria hydropiper, plant, family Polygonaceae, edibility, Polygonum hydropiper, search, Kingdom, Phylum, Genus, Species, hydropiper, Water pepper, damp, shallow water, temperate zones, spice.

Defination from the web:
Water-pepper or Water pepper (Persicaria hydropiper, syn. Polygonum hydropiper) is a plant of the family Polygonaceae. ... The water-pepper has the following active ingredients: 2 bicyclic sesquiterpenoids, polygodial (tadeonal, an unsaturated dialdehyde with a ...