Hairless, medium to tall, stoloniferous, semi-aquatic plant to 1 metre, but often rather sprawling. Stem hollow and lined. Submerged leaves 3 to 4 pinnate with linear lobes, aerial leaves pinnate with 7 to 14 pairs of lanceolate toothed leaflets, the uppermost leaves small. Flowers white, 2 mm, in leaf opposed umbels 3 to 6 cm across, each usually with 10 to 20 rays. Bracts and bracteoles both present, bracts leaf like, often pinnate.

Very similar to Fool's Watercress when it isn't in flower, and often confused with it.

A white ring-mark on the petiole below the lowest pair of leaflets, which can be felt as a harder raised ring around the petiole.  Flowers have bracts and bracteoles, and are shortly stalked, in leaf-axils and terminal. 

Either obtain confirmation from a County Recorder before submitting a record, or submit detailed images showing key features.  We recommend that you take and retain a specimen; the County Recorder may wish to see this for confirmation. 

Growing in shallow, fresh water.

July to September.

Perennial.

Fairly frequent but local in lowland England, scarce elsewhere.

Fairly frequent in Leicestershire and Rutland. In the 1979 Flora survey of Leicestershire it was found in 110 of the 617 tetrads.

In the current Checklist (Jeeves, 2011) it is listed as native, locally frequent