Carex chordorrhiza (Creeping Sedge)

Plant Info
Also known as: String-root Sedge
Genus:Carex
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Habitat:sun; wet; bogs, fens, marshes, peatlands
Fruiting season:June - July
Plant height:2 to 14 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] 2 to 5 spikes at the tip of the stem, each with staminate flowers at the tip and pistillate flowers at the base (androgynous). Spikes are crowded and stalkless, appearing as a single, oval spike at the stem tip, ¼ to 2/3 inch (5 to 16mm) long. At the base of a spike is a scale-like bract that is shorter than the spike.

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

[photo of sheath and ligule] Leaves are alternate, few, erect to ascending, all near the base, 1 to 2.5 mm wide. Stem leaf sheaths are concave at the tip, brownish to translucent white. Stems are single, slender, weakly 3-sided, mostly smooth except near the tip, and longer than the leaves. Basal sheaths are brown and scaly.

[photo of stolons] Vegetative stems are initially erect but elongate up to 4 feet at maturity, then become prostrate (stolons) and root at the nodes, forming extensive colonies. Fertile stems arise from the nodes the next season.

Fruit: Fruit type: seed without plume

[photo of mature spikes] Fruit develops in late spring to early summer, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. Spikes each contain 1 to 5 fruits that are crowded on the stalk and mostly ascending.

[photo of perigynia, scale and achene] Pistillate scales are broadly egg-shaped with a pointed tip, brown with a pale midvein and translucent edging, about as wide and long as the perigynia, mostly covering it. Perigynia are 2 to 4 mm long, 1.4 to 2.2 mm wide, distinctly veined on both surfaces, hairless, thick-walled but spongy at the base, glossy dark reddish-brown at maturity, oval-elliptic with a short, toothless beak. Achenes are lens-shaped and nearly fill the perigynia.

Notes:

Carex chordorrhiza is a circumboreal species of bogs, fens and peatlands, uncommon to rare in much of its North American range, though in favorable habitat it can be quite abundant and is found in about half of Minnesota's counties.

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 chordorrhiza is the lone member of the Chordorrhizae section in North America; some of the section's common traits are: not clump-forming, colony forming with long stolons, basal sheaths brown and not fibrous, leaves hairless and M-shaped in cross-section when young, 2 to 7 stalkless spikes with staminate flowers at the tip (androgynous), perigynia hairless, distinctly veined, rounded at the tip with a toothless beak, achenes lens-shaped.

Carex chordorrhiza should not be confused with any other sedge in Minnesota; the habit of new stems arising from the nodes of old prostrate stems is a unique trait, but taken in combination with the glossy, strongly veined perigynia in what often appears to be a single terminal spike, plus the wet habitat, separate it from all others. While the glossy, veined perigynia, terminal spikes and colony-forming habit may resemble Carex obtusata, it is only found in dry, sandy soils mostly in our northwestern counties and spreads by rhizomes (underground stems) rather than stolons (above ground stems).

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More photos

Photos courtesy Peter M. Dziuk taken in Lake County. Photos courtesy Steve Eggers taken in Mille Lacs County.

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