Spirodela polyrhiza

(L.) Schleid. 1839

This floating aroid was in the family Lemnaceae,
Until the family was included to Araceae in 2005.
You can find another spelling of the specific name: polyrrhiza.

The plant inhabits ponds and troughs.

The plant has no leaves.	It consists of leaf-shaped segments
Differently than Lemna it has many roots	The underside of the segments is red.

W. Armstrong: Spirodela polyrrhiza, images