View in other NatureServe Network Field Guides
NatureServe
Montana
Utah
Wyoming
Idaho
Wisconsin
British Columbia
South Carolina
Yukon
California
New York
Shining Flatsedge - Cyperus bipartitus
Other Names:
Cyperus rivularis
State Rank Reason (see State Rank above)
Cyperus bipartitus is rare in Montana. Plants are known from about six collections from the Bitterroot Valley. Population data is poorly documented, and trends are unknown. At five of the occurrences, observations were made over 30 years ago, and it is unknown if plants still exist at these sites. Non-native plant species may be a threat, but data is not available. Plants may be under-collected or under-reported, and are difficult to distinguish from related Cyperus species.
Revisits to known occurrences are needed to bring forth data on presence/absence, population parameters, habitat conditions, and potential threats.
General Description
Caespitose annual. Stems ascending to erect, 2–8 cm. Leaves mainly basal, 0.5–2 mm wide, U-shaped in cross-section. Inflorescence of hemispheric spikes of subsessile spikelets. Spikelets compressed, 3–15 mm long. Scales purplish, 2–2.5 mm long with rounded, minutely apiculate tips and obscure veins. Flowers: stamens 2 or 3; style 2-branched. Achene obovate, black, ca. 1 mm long, 2-sided, apiculate (
Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Phenology
Fruit mature in August-September.
Diagnostic Characteristics
Cyperus acuminatus, C. aristatus, and C. erythrorhizos all have scales with pointed or short, awn-tipped scales, unlike the blunt scale of C. rivularis.
Species Range
Montana Range
Range Descriptions
Native
Range Comments
Throughout temperate North America to S. America. Known from Ravalli County (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Observations in Montana Natural Heritage Program Database
Number of Observations: 7
(Click on the following maps and charts to see full sized version)
Relative Density
Recency
(Observations spanning multiple months or years are excluded from time charts)
Habitat
Wet, often gravelly shores of rivers, lakes and ponds in the valley zone.
National Vegetation Classification System Groups Associated with this Species
Wetland and Riparian
Alkaline - Saline Wetlands
Riparian Shrubland
Wet Meadow and Marsh
Stewardship Responsibility
Threats or Limiting Factors
Reported threats to Montana's populations of Shining Flatsedge include the potential for negative impacts from non-native plant species. However, data on impacts is not available.
References
- Literature Cited AboveLegend:
View Online Publication- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
MTNHP Threat Assessment. 2021. State Threat Score Assignment and Assessment of Reported Threats from 2006 to 2021 for State-listed Vascular Plants. Botany Program, Montana Natural Heritage Program, Helena, Montana.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?- Lesica, P., M.T. Lavin, and P.F. Stickney. 2022. Manual of Montana Vascular Plants, Second Edition. Fort Worth, TX: BRIT Press. viii + 779 p.
- Web Search Engines for Articles on "Shining Flatsedge"
