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Short-pointed Flatsedge - Cyperus acuminatus
State Rank Reason (see State Rank above)
Cyperus acuminatus appears to be very rare in Montana. Plants are known from a single 1985 collection from Sanders County and a single historical collection from the vicinity of Great Falls. A 1990 observation from Missoula County is most likely incorrect and referrable to one of three related species collected from that site. Little else is known about the species in Montana. Plants may be under-collected, under-reported, and are difficult to distinguish from related Cyperus species.
Revisits to the Sanders County and the reported Missoula County sites are needed to bring forth information on presence/absence. If found, data on population parameters, habitat conditions, and potential threats are needed.
General Description
Caespitose annual. Stems ascending to erect, 2–5 cm. Leaves basal, 0.5–1 mm wide, U-shaped in cross-section. Inflorescence of hemispheric spikes of sessile spikelets. Spikelets flattened, 3–7 mm long. Scales acuminate, yellowish, 1–2.5 mm long, 3-veined with short ascending tips. Flowers: stamen 1; style 3-branched. Achene narrowly obovate, 3-sided, brown, ca. 1 mm long (
Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Phenology
Fruit mature in August-September.
Diagnostic Characteristics
Cyperus acuminatus may be distinguished from other annual members of the genus by its globose heads, solitary stamen, and short-pointed (rather than long) flower bracts, which have only 3 veins.
Species Range
Montana Range
Range Descriptions
Native
Range Comments
Throughout the U.S., Mexico. Known from Cascade and Sanders counties (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Observations in Montana Natural Heritage Program Database
Number of Observations: 3
(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 soil of pond margins, lakes, and sloughs in the valleys and on the plains.
National Vegetation Classification System Groups Associated with this Species
Wetland and Riparian
Alkaline - Saline Wetlands
Riparian and Wetland Forest
Riparian Shrubland
Wet Meadow and Marsh
Stewardship Responsibility
Threats or Limiting Factors
Reported threats to Montana's populations of Short-pointed Flatsedge have not been identified.
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 "Short-pointed Flatsedge"
