Spirodela polyrhiza

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

Link to: W. Armstrong's page on this species