Carex ormostachya (Necklace Spike Sedge)

Plant Info
Also known as: Necklace Sedge
Genus:Carex
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Status:
  • State Special Concern
Habitat:part shade, shade, sun; moist to dry; deciduous, coniferous or mixed forest, clearings, bluffs, disturbed soil
Fruiting season:June - July
Plant height:10 to 18 inches
Wetland Indicator Status:none
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 1/3 to about ¾ inch long at the top of the stem. Below the staminate spike are usually 3 (occasionally 4) cylindric, erect to ascending, all-pistillate spikes each up to ¾ inch long, the uppermost 1 or 2 stalkless or short-stalked, near but not crowding the staminate spike and not over-topping it. Lower pistillate spikes arise singly from the nodes on the upper half of the stem on erect stalks up to 2½ inches long. Pistillate spikes each have a leaf-like bract at the base of the stalk that may over-top the terminal spike, the longest bract 4+ inches long; the uppermost bract is much shorter and narrower than the lower bracts.

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

[photo of bract sheath and ligule] Leaves are basal and alternate, 4 to 11 inches long, 3.5 to 12 mm wide, erect to floppy, and shorter than the flowering stem. Stem leaf sheaths loosely wrap the stem and are papery, translucent whitish; bract sheaths are 2-lobed at the tip and smooth along the angles. The ligule (membrane where the leaf joins the sheath) is longer than wide. Leaves are hairless, M-shaped in cross-section when young, and have a prominent, raised midrib on the underside.

[photo of basal sheaths] Bases are wrapped in a sheath that is not fibrous and usually has at least some red-purple coloring, though it may be faint. Stems are slender, 3-sided and slightly winged along the angles, hairless and smooth, ascending to sprawling, rarely erect, and may elongate up to 18 inches at maturity. Not all plants produce flowering stems. Plants form loose to dense clumps.

Fruit: Fruit type: seed without plume

[close-up of mature spike] Fruit develops in late spring through early summer, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. Pistillate spikes have 6 to 18 fruits, the perigynia ascending, loosely arranged, typically overlapping but not crowded on the upper spike and more widely spaced towards the base.

[photo of perigynia, scale and achene] Pistillate scales are whitish to light brown with a green midrib, the midrib usually extending to a short awn, and mostly shorter than the perigynia though the awn may occasionally extend beyond it. Perigynia are green to yellowish-green, 2.2 to 3(3.5) mm long, 1.2 to 1.6 mm wide (about twice as long as wide), 2-ribbed with 25+ veins (best seen when dry), hairless, not much inflated, asymmetrically urn-shaped, tapering to a spongy base with an abrupt taper to a short, toothless beak that is a bit off-center and usually strongly bent. Achenes are 2 to 2.8 mm long, weakly 3-sided in cross-section, widest at or above the middle, rounded at the tip and tapering at the base.

Notes:

Carex ormostachya is an uncommon sedge in Minnesota, where it reaches the southwestern edge of its range. It's been found in a variety of soil types from wet to dry, rocky to sandy to loamy, usually with some tree cover but occasionally in more open spaces. We encountered it on both a steep, rocky, wooded slope and the open, sandy/gravelly, disturbed soils of an old clear-cut area. According to the DNR, biological surveys of the northern counties have only discovered 16 populations to-date; it was listed as a Special Concern species in 2013.

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 ormotstachya is in the Laxiflorae section; some of its common traits are: usually densely clump forming, short to long rhizomatous, stems slightly winged along the angles, basal sheaths brown or purple and not fibrous, leaves M-shaped in cross-section when young, leaves hairless, widest leaves 5+ mm, 3 to 6 spikes, terminal spike all staminate, lateral spikes all pistillate, lateral spikes subtended by a long-sheathing leaf-like bract, perigynia hairless, generally urn-shaped and tapering to a spongy base, distinctly 8+ veined and abruptly beaked, achenes 3-sided with 3 stigmas, usually growing in woodlands.

Carex ormostachya is distinguished from other Carex species by the combination of: clump forming, basal sheaths at least slightly purple-tinged, leaves 3.5 to 12 mm wide and shorter than the flowering stems, bract sheaths smooth along the edges, usually 4 spikes, terminal spike all staminate, the uppermost 1 or 2 pistillate spikes near but not crowding the staminate spike, pistillate spikes loosely arranged and perigynia often not overlapping on the lower spike, perigynia asymmetrical, usually 3mm long or less with 25+ prominent veins (best seen when dry), a short beak that is strongly bent, weakly 3-sided achenes.

Carex ormostachya is probably most similar to Carex blanda, which has green to brown basal sheaths, bract sheaths rough along the angles, more tightly arranged pistillate spikes, larger perigynia (to 4mm long), the uppermost pistillate spikes crowd and at least partially obscure the staminate spike, and the distribution of those two species barely overlap. The loosely arranged pistillate spikes are more similar to Carex leptonervia, which has brown basal sheaths and perigynia that is essentially nerveless except for 2 prominent ribs and may have a longer beak. The loose spikes may possibly resemble those of Carex tetanica, which is colony-forming, not much clump-forming, and typically found in sedge meadows and other wet, open habitats.

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More photos

Photos by K. Chayka taken in Pine County. Photos courtesy Peter M. Dziuk taken in Cook and Pine counties.

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