Clustered Bur-reed (Sparganium glomeratum)

Life history

Species overview

Clustered Bur-reed (Sparganium glomeratum), a Wisconsin Threatened plant, is found in cold ditches and pools within sedge meadows, willow-alder thickets and, occasionally, tamarack stands on the Lake Superior clay plain. Blooming occurs late June through late July; fruiting occurs late July through early September. The optimal identification period for this species is early July through early September.

Synonyms: None

Identification

• Distinguishing characteristics: 1 or 2 staminate heads abutting the upper pistillate head; achene shining.
• Flower characteristics: Inflorescence simple, occasionally with a basal branch; flowers unisexual; pistillate heads several, sessile 1.5 to 2 cm thick when ripe; staminate head solitary or sometimes 2, abutting pistillate heads below.
• Fruit characteristics: Achene brown, shining, fusiform body, 3 to 4 mm, slighly constricted below the middle, tapering to a straight or slightly curved beak 1.5 to 2 mm.
• Leaf characteristics: Flat or weakly keeled, 3 to 8 mm wide; bracteal leaves dilated at the base.

Phenology

• Blooming phenology: late June through late July
• Fruiting phenology: late July through early September
• Optimum time to identify: The optimal identification period for this species is early July through early September

Other

• Growth form: Aquatic forb-emergent/floating
• Vegetative reproduction:
• Life cycle: Perennial
• Comments: Associated Species: Salix petiolaris, Alnus rugosa, Calamagrostis canadensis, Cornus stolonifera, Petasites sagittatus, Eleocharis nitida, Ranunculus gmelinii.

State status

Status and Natural Heritage Inventory documented occurrences in Wisconsin

The table below provides information about the protected status - state and federal - and the rank (S and G Ranks) for Clustered Bur-reed (Sparganium glomeratum). See the Working List Key for more information about abbreviations. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. The map is provided as a general reference of where this species has been found to date and is not meant as a range map.

Habitats and landscapes

The Natural Heritage Inventory has developed scores indicating the degree to which each of Wisconsin's rare plant species is associated with a particular natural community or ecological landscape. This information is similar to that found in the Wildlife Action Plan for animals. As this is a work in progress, we welcome your suggestions and feedback.

General habitat information

• Habitat description: Found in cold ditches and pools within sedge meadows, willow-alder thickets and, occasionally, tamarack stands on the Lake Superior clay plain.
• Soils: Wet soils.

Natural communities

This table lists the natural communities that are associated with Clustered Bur-reed. Scores for natural community associations are: "significant" association (score=3), "moderate association" (score=2) or the species can be present but is only weakly associated with the community (score=1).

Ecological landscapes

This table lists the ecological landscape association scores for Clustered Bur-reed. The scores (3=High, 2=Moderate, 1=Low, 0=None) also correspond to the map.

Species guidance

The Endangered Resources Program has developed avoidance measures and management guidelines for plants on the Natural Heritage Working List. These are a work in progress, and we welcome your suggestions and feedback. Sources used in developing this information can be found here.

Avoidance measures

These are specific actions designed to avoid "take" (mortality) of this species.

• Avoid known individual plant locations and conduct operations elsewhere when they are least likely to cause damage. Ideally, this would involve frozen, snow-covered ground. However, in areas of the state where frozen conditions are unreliable, very dry soils late in the growing season might be the best available alternative. Consult with a biologist, if needed.
• Avoid broadcast spraying of herbicides; use care with spot spraying.

Management guidance

Management guidelines are additional considerations that may help maintain or enhance habitat for this species

• Minimize disturbance to hydrology, including soil disturbance from rutting.
• Survey for and control invasive plants prior to conducting timber operations, as these can be spread by vehicles and often respond vigorously to increased light; see forestry BMPs for invasive species.

Other resources

Links to additional Clustered Bur-reed information

Other links related to vascular plants (all exit the DNR website)

• Wisconsin Flora
• NatureServe Explorer
• Atlas of Wisconsin Prairie and Savanna Flora - Wisconsin State Herbarium
• USDA - NRCS Plants Database
• USGS Midwestern Wetland Flora - field office guide to plant species
• eFloras
• Cofrin Center for Biodiversity Herbarium
• Intermountain Herbarium Grasses of North America
• Orchids of Wisconsin

Photos

Click to view a larger version. Please considering donating a photo to the Natural Heritage Conservation Program for educational uses. Photo use