Information on Lesser Marshwort

Common Name: Lesser Marshwort
Scientific Name: Apium inundatum
Irish Name: Smaileog bháite
Family Group: Apiaceae
Distribution: View Map (Courtesy of the BSBI)
Flowering Period


Click for list of all flowering by month
Lesser Marshwort is not easily confused with other wild plants on this web site.


Lesser Marshwort is a creeping, prostrate perennial plant which roots at nodes along its slender stems, sometimes submerged, sometimes floating. Growing in wet, bare, muddy pools, ditches and shallow water, it bears umbels of small, white, five-petalled flowers in June and July. With two forms of leaves, its lower leaves are bi-pinnate, narrow and thread-like while the upper leaves are pinnate, having broader segments. This is a native plant which belongs to the Apiaceae family.

I first recorded and photographed this little plant growing close to the Vartry Reservoir at Roundwood, Co Wicklow in 2010.

If you are satisfied you have correctly identified this plant, please submit your sighting to the National Biodiversity Data Centre

Marshwort, Lesser
Marshwort, Lesser

This plant would seem to be on the decline in the UK due to widespread drainage of wet areas.