Unbranched bur-reed (Sparganium emersum)

Unbranched bur-reed
IUCN Red List species status – Least Concern LEAST

Top facts

  • The genus name of the unbranched bur-reed, Sparganium, means ‘band’ in Greek, referring to the ribbon-like leaves of the plants in this genus.
  • The unbranched bur-reed is a perennial species, with individuals generally living for over two years.
  • The large range of the unbranched bur-reed includes Europe, Asia and North America.
  • The strong roots of the unbranched bur-reed ensure that it is not uprooted in fast-flowing water.
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Unbranched bur-reed fact file

Unbranched bur-reed description

GenusSparganium (1)

The genus name of the unbranched bur-reed (Sparganium emersum), means ‘band' in Greek, referring to the ribbon-like leaves that are a feature shared by all members of the genus (3). The long, broad leaves of this species (4) are generally rather limp and float on the surface of the water (2).

A dioecious species (4), the female and male flowers of the unbranched bur-reed are borne on separate inflorescences, on which there are either between one and six pistils or three and seven stamens (2). The pistils are positioned beneath the stamens on the stem (4), and the leaves are significantly longer than the inflorescences (5). The achene of the unbranched bur-reed is spherical and the upper half is covered in spindle-like appendages that are not present on the lower surface, which is bare and patterned with red specks (5) (6).

Rubanier émergeant, Rubanier simple.
Length: up to 2 m (2)

Unbranched bur-reed biology

Very little is known about the biology of the unbranched bur-reed, although it is known to reproduce asexually by means of underground rhizomes (4). The seeds produced by this species are viable, but sexual reproduction is rare due to the unsuitable substrate within its habitat (8). The rhizomes also function as an anchor to prevent the plant from being uprooted by fast-flowing water (8). The unbranched bur-reed generally flowers between late spring and early autumn (2) and is perennial, with individuals usually living for more than two years (4).


Unbranched bur-reed range

The unbranched bur-reed is found in China, Japan and throughout Europe, where it is most common in western and central areas, but is rare in areas close to the Mediterranean Sea (1). This species also occurs across North America, although it is absent from the south-central and south-eastern United States (7).


Unbranched bur-reed habitat

A plant of still or slow-flowing water bodies (8), the unbranched bur-reed is usually found in lakes, swamps (1) (5) (6), bogs, marshes, streams and ditches (5) (6). Although it frequently grows in lowland areas, this species has been found up to elevations of 3,000 metres (2) and it is able to grow in water up to 1 metre deep (8).


Unbranched bur-reed status

The unbranched bur-reed is classified as Least Concern (LC) on the IUCN Red List (1).

IUCN Red List species status – Least Concern


Unbranched bur-reed threats

The unbranched bur-reed is a widespread and abundant species and there are not currently thought to be any threats to its long-term survival (1). Certain populations in France, however, have declined due to changes in hydrologic regimes and the introduction of an herbivorous fish species (9).


Unbranched bur-reed conservation

The unbranched bur-reed is listed as endangered in Illinois and Ohio (7), although there are not known to be any conservation measures currently in place for this species (1).


Find out more

Find out more about the unbranched bur-reed:

Find out more about North American plant conservation:



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A simple single-seeded fruit that falls from the plant in one piece. Achenes usually in occur in clusters.
Of asexual reproduction: reproduction that does not involve the formation of sex cells (‘gametes’). In many species, asexual reproduction can occur by existing cells splitting into two, or part of the organism breaking away and developing into a separate individual. Some animals, including vertebrates, can also develop from unfertilised eggs; this process, known as parthenogenesis, gives rise to offspring that are genetically identical to the parent.
Male and female flowers are borne on separate plants.
A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ scientific species name; the second part is the specific name.
Having a diet that comprises only vegetable matter.
The reproductive shoot of a plant, which bears a group or cluster of flowers.
A plant that normally lives for more than two years. After an initial period, the plant usually produces flowers once a year.
The female reproductive organ of a flowering plant, consisting of a stigma (the pollen receptor), style (a stalk connecting the stigma with the ovary below), and ovary (encloses the ovules).
An underground, horizontal plant stem that produces roots and shoots.
The male reproductive organ of a flower. Each stamen is comprised of an anther (the pollen-producing organ) and a filament (stalk).


  1. IUCN Red List (April, 2014)
  2. Flora of North America - Sparganium emersum (April, 2014)
  3. Lahring, H. (2003) Water and Wetland Plants of the Prairie Provinces. Canadian Plains Research Center, Regina, Saskatchewan.
  4. Burke Museum of Natural History - Sparganium emersum (April, 2014)
  5. University of Wisconsin-Madison - Sparganium Identification Key and Species Descriptions (April, 2014)
  6. University of Michigan Herbarium - Sparganium emersum (April, 2014)
  7. United States Department of Agriculture - Unbranched bur-reed (April, 2014)
  8. Centre for Ecology and Hydrology - Information Sheet Sparganium emersum Unbranched Bur-Reed (April, 2014)
  9. Syndicat Mixte du Rhône des Îles et des Lônes - Sparganium emersum (April, 2014)

Image credit

Unbranched bur-reed  
Unbranched bur-reed

© Philippe Clement / naturepl.com

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