Branched bur-reed  (Sparganium erectum)

Common and widespread: not threatened (3).

Branched bur-reed is an aquatic emergent plant that grows rooted in the mud at the margins of waterbodies (4). The narrow, smooth and keeled leaves are erect and triangular in cross-section (2). The globular flowers are produced on a branching spike hence the name ‘branched’ bur-reed. Flowers at the tip of the spike are male whereas those further down are female (4). The female flowers take on a bur-like appearance before breaking up into distinct fruits (5). The fruits are small, dry and spongy and contain 1-2 seeds (4).

This native bur-reed is widespread throughout Britain, reaching altitudes of 425 m (3). It is absent from Shetland (2). It is also found in most northern temperate areas of the world (2), but is absent from eastern North America (3).

You can view distribution information for this species at the National Biodiversity Network Gateway.

Typically found growing in a narrow band at the margins of lakes, rivers, streams, ditches and canals. Occasionally, large clumps of branched bur-reed may occur in swampy habitats. Cattle graze on this species, and so it is unusual to find branched bur-reed on banks where livestock graze (3).

Branched bur-reed is a perennial species that flowers from June to August (1). The leaves arise from rhizomes and die back at the end of each year (4). Although insects do visit the flowers, they are only attracted to male flowers, and so pollination by insects is not important. Pollination is mainly by wind, although self-fertilisation may occur. The fruits can float for a number of months, which aids in their dispersal. They germinate under water, but seedling survival is poor. The plants can also spread (by vegetative reproduction) from the rhizomes (6).

This species is not threatened.

Conservation action is not required for this common species.

There may be further information about this species available via the National Biodiversity Network Gateway.

For more on British native plants and for details of how to get involved in plant conservation, visit the website of Plantlife the wild plant charity:
www.plantlife.org.uk