Carex trichocarpa (Hairy-fruited Sedge)

Plant Info
Also known as:
Genus:Carex
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Habitat:sun; wet; floodplains, wet meadows, swales, fens, seeps, marshes
Fruiting season:June - August
Plant height:16 to 48 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: 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; rarely a staminate spike will have a few pistillate flowers at the tip (gynaecandrous). 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. 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 sheath and ligule] Leaves are basal and alternate, 3 to 8.8 mm wide, often over-topping the terminal spike, mostly arching, and hairless but rough along the edges. Stem leaf sheaths are hairless, concave to U-shaped and thickened at the tip, the thickened portion dark reddish to purplish-brown and glossy, the darkened color often extending down the front of the sheath. Stem sheaths do not become fibrous with age. The ligule (membrane where the leaf joins the sheath) is usually about as long as wide and rounded at the tip.

[photo of lower stems and purple basal sheaths] Bases are wrapped in a sheath that is reddish to purple and becomes fibrous with age. Stems are erect, 3-sided in cross-section, and rough-textured especially on the upper stem. Not all plants produce flowering stems; vegetative stems are firm and solid and usually taller than flowering stems. Plants are loosely clump forming and may form extensive colonies from long rhizomes.

Fruit: Fruit type: seed without plume

[close-up of mature spike] Fruit develops in early to mid-summer, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. Perigynia are ascending to spreading and overlapping on the spike, sometimes loosely so. Each pistillate spike contains up to 40 fruits.

[photo of perigynia, scale 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, and about half as long as the perigynia. Perigynia are 5 to 11.5 mm long, 2.1 to 3.9 mm wide, green to light brown at maturity, sparsely to densely short-hairy, 12 to 22-veined, inflated but firm, the body narrowly teardrop-shaped and round in cross-section, tapering 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, 1.2 to 2.5 mm long, maturing to dark yellow-brown.

Notes:

Carex trichocarpa is a sedge of marshes, wet meadows, and floodplains and reaches the western edge of its range in Minnesota. It often forms nearly pure stands of vegetative shoots, with few flowering plants.

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 trichocarpa is distinguished from all other Minnesota sedges by the combination of: stem bases red to purplish and becoming fibrous, stem sheaths thickened and glossy dark purplish at the tip and not fibrous, usually 3 staminate spikes, 2 to 4 pistillate spikes widely separated from staminate spikes, hairy perigynia 5+mm long with straight to slightly spreading teeth. It resembles Carex atherodes, which typically has hairy sheaths and hairless perigynia. Vegetative forms may be indistinguishable from Carex laeviconica, which was once considered the same species but has hairless perigynia and fibrous stem sheaths that lack the dark coloring at the tip, and with which C. trichocarpa has been known to hybridize.

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More photos

Photos courtesy Peter M. Dziuk taken in Winona County. Other photos courtesy Steve Eggers.

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