In County Longford  the watercress plant was  traditionally known as St Patrick’s Cabbage.

Watercress  is  peppery tasting plant and was traditionally  an important food in Ireland.  It was also held to have medicinal properties.

References

Mac, Coitir, N. 2006.  Irish Wild Plands, Myths, Legends and Folklore.  Cork: The Coillins Press.