Carex gynocrates (Northern Bog Sedge)

Plant Info
Also known as: Feminine Sedge
Family:Cyperaceae (Sedge)
Life cycle:perennial
Habitat:part shade, shade; wet; bogs, conifer swamps, alder thickets
Fruiting season:June - July
Plant height:2 to 10 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 spike] A single spike up to about ½ inch long at the top of the stem. Within a population, some spikes may have staminate (male) flowers at the tip and pistillate (female) flowers below (androgynous), some spikes may be all-staminate, but most spikes are all-pistillate. A bract at the base of the spike is absent.

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

[photo of leaves and stems] Leaves are alternately attached to the stem near the base, each up to 6 inches long, up to .7 mm wide, thread-like and shorter than the flowering stems. Bases are wrapped in a brown sheath that is not fibrous. Stems are single or a few together, mostly erect, round to weakly 3-sided in cross-section, very slender, elongating up to about 10 inches at maturity and remain longer than the leaves. Plants create mats or loose colonies from thread-like rhizomes.

Fruit: Fruit type: seed without plume

[close-up of mature spike] Fruit develops in late spring to mid-summer, the spike forming a cluster of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. Each pistillate spike contains up to 15 fruits that are crowded to loosely arranged and become widely spreading to reflexed (downward pointing) at maturity.

[photo of perigynia, scales and achene] Pistillate scales are lance to egg-shaped with a pointed tip, brown to reddish-brown with a green midvein that turns brown, and slightly shorter than the perigynia. Perigynia are 2.9 to 3.4 mm long, 1.2 to 1.7 mm wide, strongly veined on the front and more weakly veined on the back, yellowish to chestnut brown when mature, leathery but may be spongy at the base, oblong-oval, rounded at the base, tapering to a short beak that is usually smooth along the edges, sometimes slightly rough, and obscurely toothed at the tip. Achenes are 1.5 to 1.7 mm long, 1 to 1.2 mm wide, oval to nearly round, 2-sided lens-shaped


Carex gynocrates is an occasional sedge of shady bogs, conifer swamps and alder thickets, often growing on Sphagnum hummocks, though sometimes found in more open places. It has a circumboreal distribution and, except for alpine populations in the western US, reaches the southern edge of its range in Minnesota.

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 gynocrates is the lone member of the Physoglochin section in the contiguous US and Canada; some of the section's common traits are: rhizomatous, basal sheaths brown and not fibrous, leaves thread-like or V-shaped in cross-section when young, 1 spike per stem, spike with staminate flowers at the tip (androgynous) or of a single sex, perigynia usually spreading at maturity, spongy at the base, hairless, veined on at least 1 side, beak to 1mm long, achenes lens-shaped with 2 stigmas.

Carex gynocrates is distinguished from all other Carex species in Minnesota by the small stature, thread-like foliage, single spike (most of which in a population are all-pistillate), with widely-spreading perigynia that are beaked and veined, lens-shaped achenes, and the mat-forming growth particularly in shady, mossy places. While it should not be easily confused with any other species, it does have a vague resemblence to a few others. Carex leptalea, which may grow side-by-side with C. gynocrates, has beakless, appressed perigynia. Carex exilis has a single spike with spreading perigynia like C. gynocrates, but is a taller, clump-forming plant of open fens and peatlands, mixed-sex spikes have pistillate flowers at the tip (gynecandrous) rather than staminate, and perigynia are strongly serrated along the beak edges. Carex chordorrhiza has been occasionally mistaken for C. gynocrates, but has multiple spikes crowded at the tip of the stem, perigynia are mostly erect to ascending, and is found in open, sunny places.

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More photos

Photos by K. Chayka taken in Becker County. Photos courtesy Peter M. Dziuk taken in Becker and Roseau counties. Photos courtesy Steve Eggers taken in Aitkin County.


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