Short-pointed Flatsedge - Cyperus acuminatus
State Rank Reason (see State Rank above)
Rare in Montana, where it is currently known from only 2 collections in the western portion of the state.
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
Fruit mature in August-September.
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.
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:
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(Observations spanning multiple months or years are excluded from time charts)
Wet soil of pond margins, lakes, and sloughs in the valleys and on the plains.
Ecological Systems Associated with this Species
Threats or Limiting Factors
STATE THREAT SCORE REASON
Threat impact not assigned because threats are not known (MTNHP Threat Assessment 2021).
- 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.