Watercress is a perenniel aquatic plant native to Europe and central Asia, and are members of the cabbage family. It grows between 15 and 60 centimetres with alternate, oval shaped leaves that are shiny and dark green with smooth edges. They grow best in water that is approximately 10 centimetres deep, with succulent, fleshy, hollow stems and with fibrous roots. Its flowers are white with 4 petals, which bloom from April to June. It has a peppery, tangy mild mustard flavour and is amongst the oldest edible vegetables known to man.