Branched bur-reed  (Sparganium erectum)

Female branched bur-reed flowers

Facts

Kingdom Plantae
Phylum Anthophyta
Class Liliopsida
Order Typhales
Family Sparganiaceae
Genus Sparganium (1)
Size Leaf width: 10 - 15 mm (2)
Height: 50 - 150 cm (2)

Status

Common and widespread: not threatened (3).

Description

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).

Range

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).

Habitat

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).

Biology

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).

Threats

This species is not threatened.

Conservation

Conservation action is not required for this common species.

Further Information

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

Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

Perennial: plants that live for at least three seasons; after an initial period they produce flowers once a year.
Rhizomes: rhizomes are thickened, branching, creeping storage stems. Although most rhizomes grow laterally just along or slightly below the soil's surface, some grow several inches deep. Roots grow from the underside of the rhizome, and during the growing season new growth sprouts from buds along the top. A familiar rhizome is the ginger used in cooking.
Vegetative reproduction (or propagation): type of asexual reproduction (reproduction without recombination of genetic material) that results in the propagation of plants using only the vegetative tissues such as leaves or stems. The resulting plant is genetically identical to the original plant. A well-known example of this is the reproduction of strawberry plants from ‘runners’.

References

  1. National Biodiversity Network Species Dictionary (September 2003):
    http://www.nhm.ac.uk/nbn
  2. Clapham, A.R., Tutin, T.G., and Moore, D.M. (1987) Flora of the British Isles 3rd Edition. Cambridge University Press, Cambridge.
  3. Preston, C.D., Pearman, D.A. and Dines, T.D. (2002) New Atlas of the British and Irish Flora. Oxford University Press, Oxford.
  4. Stace, C. (1991) New Flora of the British Isles. Cambridge University Press, Cambridge.
  5. Habitas.org (December 2003):
    http://www.habitas.org.uk/flora/species.asp?item=2361
  6. Offwell Woodland and Wildlife Trust (December 2003):
    http://www.countrysideinfo.co.uk/wetland_survey/burreed.htm