Carex laeviconica (Smooth-cone Sedge)

Plant Info
Also known as: Plains Slough Sedge, Long-tooth Lake Sedge
Family:Cyperaceae (Sedge)
Life cycle:perennial
Habitat:sun; wet; riverbanks, marshes, wet ditches, shores, floodplains, wet meadows, prairie potholes
Fruiting season:June - July
Plant height:12 to 42 inches
Wetland Indicator Status:GP: OBL MW: OBL NCNE: OBL
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Spikes: Flower shape: indistinct Cluster type: spike

[photo of spikes] Separate staminate (male) and pistillate (female) spikes, with 2 to 5 (usually 3) staminate spikes up to 2 inches long clustered at the tip of the stem. Below the staminate spikes are 2 to 4 erect to ascending, cylindric pistillate spikes, each 1 to 3 inches long, well separated from terminal spikes and each other, the upper stalkless and the lower on short, erect stalks. Pistillate spikes sometimes have a few staminate flowers at the tip (androgynous). At the base of each pistillate spike is a leaf-like bract that often over-tops the terminal spikes.

Leaves and stems: Leaf attachment: alternate Leaf attachment: basal Leaf type: simple

[photo of stem sheath and ligule] Leaves are alternate, 3 to 8 mm wide, often over-topping the terminal spike, and mostly arching. Stem leaf sheaths are concave to U-shaped at the tip, the front whitish to brown, splitting into fibers with age. The ligule (membrane where the leaf joins the sheath) is about as long as wide and rounded at the tip.

[photo of red, fibrous base] Bases are wrapped in a sheath that is reddish to purple and fibrous, the fibers connected and forming a ladder pattern (ladder-fibrillose). Stems are mostly erect, 3-sided in cross-section, and mostly smooth but may rough on the upper stem. Not all plants produce flowering stems; vegetative stems are firm and solid. Plants are loosely clump forming and may form colonies from long rhizomes.

Fruit: Fruit type: seed without plume

[close-up of maturing spike] Fruit develops in late spring to mid-summer, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. Perigynia are mostly ascending and overlapping on the spike, often loosely arranged at the base of the spike and more crowded above. Each pistillate spike contains up to 50 fruits.

[photo of perigynia, scales and achene] Pistillate scales are lance to narrowly egg-shaped, reddish to brown with white edging and a green midrib, pointed at the tip or the midrib extending to a rough-textured awn, the scale body half or more as long as the perigynia but with the awn may be as long as the perigynia. Perigynia are 5 to 9 mm long, 1.8 to 3.3 mm wide, green to yellowish at maturity, hairless, 12 to 26-veined, inflated but firm, the body narrowly teardrop-shaped and round in cross-section, with a long taper to a straight beak with 2 straight to slightly spreading teeth 1 to 2 mm long at the tip. Achenes are weakly 3-sided in cross-section, 2 to 2.5 mm long, maturing to dark yellow-brown, with a straight, persistent style.


Carex laeviconica is a sedge of riverbanks and floodplains, less often in ditches, swales, wet meadows, and lake and pond edges. In west-central Minnesota, it is also found in prairie potholes and wet depressions.

Carex is a large genus, with over 600 species in North America and 150+ in Minnesota alone. They are grouped into sections, the species in each group having common traits. Carex laeviconica is in the Carex section; some of its common traits are: clump forming, long-rhizomatous, basal sheaths fibrous and red to brown, leaves and/or sheaths sometimes hairy, leaves M-shaped to flat in cross-section, lower leaves with cross partitions between veins (septate-nodulose), 4 to 10 spikes, terminal spike all-staminate, 1 to 5 staminate spikes, lower 2 to 5 spikes pistillate, pistillate spikes erect to ascending, thick cylindrical, all-pistillate or with a few staminate flowers at the tip (androgynous), leaf-like bract subtending pistillate spikes, perigynia  ascending, hairy or not, 12 to 26 veined, inflated, mostly teardrop-shaped with a long taper to a toothed beak, achenes 3-sided in cross-section with a long, persistent style. Members of the Carex section may resemble some species in the Paludosae or Vesicariae sections.

Carex laeviconica is distinguished from all other Minnesota sedges by the combination of: stem bases red to purplish, sheaths fibrous, especially basal sheaths, ligule rounded at the tip and about as long as wide, usually 3 staminate spikes, 2 to 4 pistillate spikes widely separated from staminate spikes, hairless perigynia with a long taper to a beak with straight to slightly spreading teeth 1 to 2mm long. It resembles the more hairless forms of Carex atherodes, which typically has hairy sheaths, ligules much longer than wide, longer teeth on the perigynia beak that are usually widely spreading. Vegetative forms may be indistinguishable from Carex trichocarpa, which was once considered the same species but has hairy perigynia and stem leaf sheaths that are thickened, glossy purplish at the tip and not fibrous, and with which C. laeviconica has been known to hybridize. Of note is that several references state Carex laeviconica is clump-forming, but our observation is that it is weakly so at best with just 1 or a few stems and few leaves.

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More photos

Photos by K. Chayka and Peter M. Dziuk taken in Houston County. Photos courtesy Steve Eggers taken in Dakota County and in Wisconsin.


Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Fred H - Saint Paul
on: 2017-09-05 17:39:28

I note that infertile stems are typically aphyllopodic (i.e. leaves not basal) with leaves coming off the stem. I find this species in wet depressions and potholes within prairies in west-central MN.

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