Photographs: The Gearagh Co.Cork
Very small umbels, 1-2cm wide, of 2-4 rayed white flowers in leaf axils.
Submerged leaves deeply tripinnate, hair-like feathery appearance. Upper leaves with three-lobed or pinnate narrow leaflets. Hairless. More/less prostrate. To 40cm.
Shallow water or waterside mud. Decreasing due to habitat loss.
Similar: Apium x moorei. Hybrid with Fools Water-cress, A. nodiflorum.
Scattered distribution in Ireland.
Photographs above: The Gearagh, Co.Cork. October 2007