Jenny Greenteeth, or Ginny Greenteeth, is a water spiritAn elemental is a type of primitive spiritual entity from the pagan past, perhaps the manifestation of a race memory, usually associated with a single place. said to inhabit pools in Cheshire, Lancashire and Shropshire.[a]A similar water demon is known as a grindylow in Yorkshire, and a Kappa in Japan. According to most accounts Jenny has the form of an old woman, lurking beneath the weeds that cover stagnant ponds; the weeds may even be her hair floating on the surface of the pond. So closely is Jenny Greenteeth associated with duckweed that in some parts of the country it is the name given to the weed itself. If children venture too close, then she reaches out of the water and drags them in to their deaths.
Recalling what she had been told as a child, one woman described Jenny as having “pale green skin, green teeth, very long green locks of hair, long green fingers with long nails, and she was very thin with a pointed chin and very big eyes”. Another said that she “had no known form, due to the fact that she never appeared above the surface of the pond”, although others claimed that she sometimes lurked in treetops. A contributor to Notes & Queries writing in 1904 reported that “I have often been told by my mother and nurse that if I did not keep my teeth clean I should some day be dragged into one of these ponds by Jenny Greenteeth, and I have met many elderly people who have had the same threat applied to them”.
The most likely source of the name Jenny Greenteeth is that it derives from the tooth-like appearance of duckweed, Lemna minor. She is probably best known today from J.K.Rowling’s Harry Potter and the Goblet of Fire, in which she is one of the creatures inhabiting the lake near Hogwarts.
Opinion among Victorian folklorists was divided between those who believed Jenny Greenteeth to be a bogey useful to anxious parents in keeping their children away from dangerous bodies of water, and those who believed her to be a remnant of ancient sacrificial practices.
The modern consensus is that Jenny Greenteeth is a nursery bogey intended to scare young children, but who in the words of Katharine Briggs, “[was] not likely to frighten anyone over eight years old”. Concerned parents invoked her to frighten children away from potentially dangerous places including railway tracks in south Cheshire, and her green teeth also served to drive home the importance of dental hygiene. As Roy Vickery of the British Museum’s Department of Botany has observed, “Jenny Greenteeth remains one of the most versatile … inhabitants of north-west England”.