Duckweed is one of the world’s smallest flowering plants, but it can form dense mats on still water, and less frequently on permanently damp mud and rock faces. It is common throughout the British Isles, apart from northern Scotland.

In northwest England the presence of duckweed indicated that the bogey Jenny, or Jinny, Greenteeth lurked below the water’s surface:

As a child about 50 years ago in the Liverpool area, I was frightened by Jenny Greenteeth, a sort of fairy, who would drag people down into deep pools. Jenny was particularly associated with pools covered with duckweed [1].

Although Jenny Greenteeth was usually unseen, in about 1920 the bogey which inhabited two pools beside Moss Pitts Lane in Fazakerley, ‘had pale green skin, green teeth, very long green locks of hair, long green fingers with long nails, and she was very thin with pointed chin and very big eyes’ [2].

Katharine Briggs, in her Dictionary of Fairies, classified Jenny as a Nursery Bogey, one of ‘a group of spirits that seem as if they had never been feared by grown-up people but had been invented expressly to warn children off dangerous ground or from undesirable activities’ [3].

1. Kensington, London, November 1979.
2. Bebington, Merseyside, November 1980.
3. Katharine Briggs, A Dictionary of Fairies, London, 1976: 313.

For further information see: A.R. Vickery, Lemna minor and Jenny Greenteeth, Folklore 94: 247-50, 1983.

Images: main, Grand Union Canal Paddington Branch, Paddington, City of Westminster, July 2014; inset, Huntingdon, Cambridgeshire, September 2015.