Information on Unbranched Bur-reed

Common Name: Unbranched Bur-reed
Scientific Name: Sparganium emersum
Irish Name: Rísheisc lom
Family Group: Sparganiaceae
Distribution: View Map (Courtesy of the BSBI)
Flowering Period


Click for list of all flowering by month
Unbranched Bur-reed could sometimes be confused with:

Bur-reed, Branched,

This is an erect plant which is quite similar to Branched Bur-reed but there are some differences. It is smaller (up to 60cm tall) and grows further out into watercourses but the main difference is that its stem is unbranched, bearing its globular flowers at the top of an unbranched stem. There are three, or more, male heads borne along this stem and these differ from those of Branched Bur-reed by being completely pale in colour, without any black tips. There are three or four female heads – pale green in colour - which are below the male flowers. The leaves of this plant species come in two forms with those above water being bright green, long, narrow and erect; there are also floating leaves and these are flat and keeled at their base.

This is a native, aquatic perennial which grows on creeping rhizomes and can be found in both still and moving water and on muddy ground. It flowers in June and July and is more likely to be found in the centre and the north of the country. It belongs to the Sparganiaceae or Bur-reed family.

I first found this plant species in August 2016 in Lough Boora, Co Offaly while on a visit with the Wexford Naturalists’ Field Club. I photographed it at the time. 

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

Bur-reed, Unbranched
Bur-reed, Unbranched

The male heads of this plant species mature after the female heads. As plants can be self-pollinated or wind-pollinated, insect pollination is not very important and insects only seem to visit male flowers.  

The plants do much better in slow-moving water as they are quite easily uprooted. They can also be eaten by cattle.