Carex pseudocyperus (Cyperus-like Sedge)

Plant Info
Also known as: False Bristly Sedge
Genus:Carex
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Habitat:sun; wet; along shores, riverbanks, swamps, marshes, swales, wet ditches, floating mats
Fruiting season:June - July
Plant height:10 to 40 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 a single staminate spike up to 3 inches long at the tip of the stem, sometimes with a few pistillate flowers at the tip (gynecandrous) or the base (androgynous) or otherwise mixed. Below the staminate spike are 2 to 6 pistillate spikes, each up to 3 inches long, cylindric, 9 to 12 mm in diameter, initially erect to ascending becoming drooping, occasionally with a few staminate flowers at the tip. The lowest pistillate spike is long-stalked and usually some distance from the one above it, the spikes becoming shorter stalked and closer together as they ascend the stem. At the base of each pistillate spike is a leaf-like bract, those of the lowest spikes significantly over-topping the terminal spike; the lowest bract is up to 20 inches long.

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

[photo of stem sheath and ligule] Leaves are basal and alternate, 4 to 13 mm wide, the upper stem leaves over-topping the terminal spike. Stem leaf sheaths are concave to U-shaped at the tip, papery whitish to light brown. The ligule (membrane where the leaf joins the sheath) is much longer than wide. Leaves are hairless, W-shaped to flat in cross-section, erect to arching.

[photo of plant base] Bases are wrapped in a brown sheath that not fibrous, with old leaves persisting from the previous season. Stems are erect to ascending, 3-sided in cross-section, and mostly smooth except rough on the upper stem. Stems can elongate up to about 3 feet at maturity. Plants form loose to dense clumps from short 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 widely spreading to angled downward (reflexed, especially near the base of the spike) and tightly packed on the spike. Each pistillate spike contains 100+ fruits.

[photo of perigynia, scale and achene] Pistillate scales are lance-oblong, white to brown tinged, with a green midrib that extends to a long rough-textured awn; awns near the base of the spike are longer than the perigynia and shorter near the tip, with the scale body usually well hidden. Perigynia are 3.4 to 6.1 mm long, 1 to 1.7 mm wide, green to brown at maturity, hairless, strongly 12 to 20-veined, stiff, leathery, not much inflated, the body narrowly lance-elliptic, tapering to a stalk-like base (stipe), gradually tapering to a short beak that has 2 erect to slightly spreading teeth up to 1 mm long at the tip. Achenes are 3-sided, maturing to light brown, oval-elliptic with a persistent style.

Notes:

Carex pseudocyperus is a common sedge of swampy or boggy areas, lake and pond shores, and riverbanks in about 3/4 of Minnesota, often in shallow water and rooted in muck.

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 pseudocyperus is in the Vesicariae section; some of its common traits are: clump forming or not, rhizomatous, hairless leaves, basal sheaths brown or red-purple, sheaths often splitting into fibers and forming a ladder shape, sheaths with cross partitions between veins (septate-nodulose), 2 to 10 spikes, terminal spike all-staminate, leaf-like bract subtending the lowest pistillate spike, perigynia mostly ascending to spreading, hairless, mostly egg to teardrop shaped, beaked and toothed, at least slightly inflated, achenes 3-sided in cross-section with a persistent style.

Carex pseudocyperus is distinguished from all other Minnesota sedges by the combination of: brown basal sheaths, pistillate spikes cylindric, spreading to drooping on slender stalks, perigynia not much inflated, strongly 12 to 20-veined and the beak with 2 erect to slightly spreading teeth up to 1mm long. The spikes of C. pseudocyperus resemble those of Carex comosa, Carex hystericina and Carex lurida, the latter two having red-purple basal sheaths where C. pseudocyperus has brown sheaths. It most closely resembles C. comosa, which has thicker spikes, 12 to 18mm in diameter, and longer teeth on the beak that are widely spreading. C. pseudocyperus rarely hybridizes with C. comosa, more frequently with C. hystericina.

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More photos

Photos by K. Chayka taken in Anoka County. Photos courtesy Peter M. Dziuk taken in Otter Tail and Pope counties. Photos courtesy Jason Husveth taken in Anoka County.

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