Carex conjuncta (Soft Fox Sedge)

Plant Info
Also known as: Jointed Sedge
Genus:Carex
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Status:
  • State Threatened
Habitat:part shade, sun; moist; floodplain forest, river banks, wet meadows, marsh edges
Fruiting season:July
Plant height:15 to 32 inches
Wetland Indicator Status:GP: FAC MW: FACW NCNE: FACW
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: panicle Cluster type: spike

[photo of spike cluster] A cluster up to 3 inches long at the top of the stem, compound with 8 to 12 branches, the lower branches usually distinct with a few stalkless spikes each and the upper branches more obscure often with a single spike. Branches are mostly overlapping but not tightly crowded except near the tip, though the lowest branch may be farther separated. All spikes are alike with staminate (male) flowers at the tip and pistillate (female) flowers at the base (androgynous). At the base of each spike is a bristle-like bract, the lowest bract longest and may be as long as the associated branch but does not over-top the terminal spike; bracts become shorter as they ascend the stem and are obscure in the uppermost spikes.

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

[photo of stem cross-section, sheath and ligule] Leaves are basal and alternate, mostly near the base, 5 to 10 mm wide, shorter than to about as long as the flowering stems. Stem leaf sheaths are convex at the tip, cross-wrinkled (rugulose) on the front, loosely wrap the stem, fragile and easily torn, translucent whitish and variably covered in reddish to purplish dots, especially along the edges and near the tip. The ligule (membrane where the leaf joins the sheath) is shorter or longer than wide, blunt to pointed at the tip. Leaves are hairless and V-shaped in cross-section when young. Bases are wrapped in a brown sheath that persists to the next season and may become fibrous. Stems are erect to ascending, strongly 3-sided with narrow wings, stout but spongy and easily compressed, rough textured at least on the upper stem, elongating up to about 30 inches at maturity. Plants are clump-forming and not colony-forming.

Fruit: Fruit type: seed without plume

[close-up of maturing 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 each contain 8 to 15 fruits that are ascending to spreading and crowded on the stalk.

[photo of perigynia, scale and achene] Pistillate scales are narrowly egg-shaped, translucent whitish and a green midrib, tapering to a pointed tip or the midrib extending to a short awn, and are about as long as or slightly shorter than the perigynia (including any awn). Perigynia are 3 to 5 mm long, about half as wide, green to greenish-brown at maturity except paler at the base, veinless on the back, distinctly 3 to 5-veined on the front, hairless, not inflated but somewhat spongy at the base, flattened on the back side, narrowly egg-shaped in outline, widest near the base, the base rounded but abruptly tapered to a short stalk-like structure (stipe), the tip tapering to a toothed beak to 1.8 mm long (shorter than the body) and is finely toothed along the edges. Achenes are up to 2.2 mm long and 1.4 mm wide, flattened lens-shaped, egg-shaped, and mature to brown.

Notes:

Carex conjunta is a very rare sedge in Minnesota, where it reaches the northern fringe of its range. According to the DNR, it was first discovered along the Cannon River in Rice County in 1976 and only recorded 3 times since; it was listed as a Threatened species in 1984 due to its rarity. In Minnesota it is has only been found in wooded floodplains but in other parts of its range it may also be found in wet meadows and marsh edges.

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 conjuncta is in the Vulpinae section; some of its common traits are: clump forming, stems usually spongy, basal sheaths fibrous or not, sheath fronts cross-wrinkled (rugose) or not, leaves hairless and V-shaped in cross-section when young, spike clusters branched (compound) or not (simple) and often crowded, 4 to 20 stalkless spikes, terminal spike with staminate flowers at the tip (androgynous), lateral spikes androgynous or all pistillate, perigynia twice or more as long as wide, widest at/near the base, the base rounded with spongy tissue, tapered at the tip to a toothed beak, flattened lens-shaped achenes. Several of these traits are shared with the Phaestoglochin and Multiflorae sections; both have perigynia widest near the middle and usually less than twice as long as wide, firm stems, and the former usually has more than 15 spikes.

Carex conjuncta is distinguished by its stems that are stout but easily compressed and strongly 3-sided with narrow wings, fragile leaf sheaths that are cross-wrinkled on the front, convex at the tip and variably red-dotted (see C. alopecoidea or C. crus-corvi for examples of the dots), cluster usually branched at least at the base, spikes/branches overlapping but not crowded, androgynous spikes, perigynia 3 to 5 mm long that are widest at/near the base, spongy and rounded at the base and tapering to a toothed beak, and pistillate scales that are nearly or about as long as the perigynia and tapered to a pointed tip, sometimes awned. Compare to species with a similar arrangement of spikes, which may have firm stems; leaf sheaths that are smooth on the front, concave at the tip or are not fragile; perigynia widest near the middle; or pistillate scales much shorter than the perigynia (including any awn).

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More photos

Photos by K. Chayka and Peter M. Dziuk taken in Rice County.

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