Carex gynandra (Nodding Sedge)
|Also known as:|
|Habitat:||part shade, sun; moist to wet; swamps, bogs, along shores, wet ditches, floodplain forest|
|Fruiting season:||June - August|
|Plant height:||18 to 60 inches|
|Wetland Indicator Status:||GP: none MW: FACW NCNE: OBL|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Separate staminate (male) and pistillate (female) spikes, with 1 to 3 staminate spikes up to 2+ inches long at the top of the stem, which occasionally have a few pistillate flowers at the tip (gynecandrous). Below the staminate spikes are 2 to 5 slender-stalked pistillate spikes, arising singly from the nodes; often some pistillate spikes have a few staminate flowers at the tip (androgynous). The stalk of the lowest spike is longest with both staminate and pistillate stalks becoming somewhat shorter as they ascend the stem, and drooping with maturity. Pistillate spikes are slender and cylindrical, up to 4 inches long, each with a leaf-like bract at the base of the stalk, the bract of the lowest spike over-topping the terminal spike. All spikes are fairly evenly spaced on the stem, except the lowest spike is typically a bit more widely separated from the one above it.
Leaves and stems:
Leaves are basal and alternate, up to 5 leaves per stem, 4 to 12 mm wide, up to 21 inches long, shorter than the flowering stem though the upper stem leaves can over-top the spikes. Stem leaf sheaths loosely wrap the stem and are papery, translucent whitish to brown-tinged, mostly straight across the top with short, stiff hairs along the edge. The ligule (membrane where the leaf joins the sheath) is longer than wide with a broad band of loose tissue around the edge. Leaves are M-shaped in cross-section when young, and hairless though slightly rough along the edges.
Bases are wrapped in a rough-textured, brown to reddish-purple sheath that becomes somewhat fibrous with maturity. Stems are stout, 3-sided and rough along the angles, erect to ascending, elongating up to 5 feet at maturity. Not all plants produce flowering stems. Plants form loose to dense clumps and may form loose colonies from creeping rhizomes.
Fruit develops in late spring through mid-summer, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. The empty staminate scales persist after fruit has dropped off. Pistillate spikes are densely packed with numerous fruits, the perigynia mostly ascending.
Pistillate scales are widest above the middle, brown with a green midrib that often extends to a long awn with rough hairs along the edge, the tip of the scale body mostly tapering or slightly rounded, the body about as long as the perigynia. Perigynia are light green tinged light brown at maturity, 1.9 to 4.2 mm long, 1.1 to 2.3 mm wide, 2-ribbed with a few weak veins, hairless, slightly inflated, oval to egg-shaped, widest at or near the middle, tapering to a short, toothless beak at the tip. Achenes are 1.5 to 1.7 mm long, lens-shaped and variously crimped on one side (occasionally both).
Carex gynandra reaches the northwestern edge of its range in Minnesota, found in wet places in our northeast 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 gynandra is in the Phacocystis section (a combination of former Acutae and Cryptocarpae sections); some of its common traits are: typically clump forming and rhizomatous, leaves V or M-shaped in cross-section when young and hairless except along the edges, spikes long and cylindric, spikes drooping on slender stalks to nearly stalkless, terminal spike usually all staminate or with a few perigynia at the tip, perigynia densely packed, green to brownish, 2-ribbed, weakly veined and short-beaked, achenes lens-shaped with 2 stigmas, growing in wetlands and other wet places.
Carex gynandra is very similar in appearance to Carex crinita, which has smooth basal sheaths, perigynia more rounded at the tip, and the body of pistillate scales are straight across or have somewhat heart-shaped lobes at the tip, where C. gynandra scales mostly taper or are slightly rounded at the top of the body, perigynia are more tapering at the tip, and its basal sheaths are rough textured. C. gynandra was once considered a variety of C. crinita: var. gynandra.
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Photos courtesy Peter M. Dziuk taken in Cook County.
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