Carex richardsonii (Richardson's Sedge)

Plant Info
Also known as:
Genus:Carex
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Habitat:sun; sandy or rocky soil; prairies, open woods, bluffs, barrens, forest edges
Fruiting season:May - June
Plant height:6 to 12 inches
Wetland Indicator Status:GP: FAC MW: UPL NCNE: UPL
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 flowering spikes] Separate staminate (male) and pistillate (female) spikes, with a single staminate spike up to 1 inch long at the top of the stem. Below the staminate spike are 2 or 3 (occasionally 4 or 5) pistillate spikes, which may have a few staminate flowers at the tip (androgynous). Lateral spikes are well-separated, narrowly cylindric, up to ¾ inch long, erect to ascending with a scale-like bract at the base. Bract blades are up to 1 inch long, dark reddish to purplish brown with pale edging and have a long, tightly wrapping sheath that is usually dark red to purple-brown, sometimes paler. The lower pistillate spikes are on straight, erect to ascending stalks up to about 2½ inches long, the upper spikes shorter stalked.

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

[photo of stem leaves of vegetative shoot] Leaves are mostly basal with a few near the base, 2 to 3.5 mm wide, hairless, flat and stiff. Stem leaves are nearly bladeless to short-bladed, the basal leaves much shorter than the flowering stems at anthesis though may be nearly as long at maturity. Stem leaf sheaths are concave, translucent whitish-green only at the tip, otherwise variously red-tinged. The ligule (membrane where the leaf joins the sheath) is about as long as wide. Leaves are V-shaped in cross-section when young with old, dead basal leaves often persisting through winter and withering away the next season.

[photo of plant base with persistent dead leaves] Bases are wrapped in a reddish to purplish-brown sheath that is not fibrous. Stems are slender, nearly round in cross-section, slightly rough. Stems can elongate up to 12 inches at maturity and are longer than the leaves. Not all plants produce flowering stems. Plants form loose clumps and loose colonies from scaly rhizomes.

Fruit: Fruit type: seed without plume

[photo of mature spike] Fruit develops in mid spring, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. The scales of staminate scales are reddish to purplish brown, lance-elliptic with a blunt or pointed tip and whitish edging. Pistillate spikes each contain 10 to 25 fruits that are erect to ascending and overlapping but not tightly crowded.

[photo of perigynia, scale and achenes] Pistillate scales are dark purplish-brown with whitish edging, lance-elliptic with a blunt or pointed tip, and as long as to rather longer than the perigynia. Perigynia are 2.2 to 3 mm long, 1 to 1.3 mm wide, hairy on the body, lack veins, are nearly round in cross-section, widest above the middle with a short, toothless beak, and tightly wrap the achene except for a fleshy base that is pale and dries to a stalk-like appendage. Achenes are about 1.75 mm long and 1.1 mm wide, generally urn-shaped, 3-sided to nearly round in cross-section, mature to dark reddish-brown.

Notes:

Carex richardsonii is an occasional sedge of open sandy prairies, forest edges, barrens and bluffs, though in Minnesota it is most often found in sandy prairies and Jack pine stands, in dry soil or soils that dry out in summer. It is one of the earliest blooming sedges, flowering in April and fruiting in May.

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 richardsonii is in the Clandestinae section (formerly Digitae); some of its common traits are: flowering in early spring, growing in clumps, basal sheaths red-purple and not fibrous, hairless leaves, widest leaves 2 to 4 mm, mostly bladeless sheaths, 2 to 5 spikes, terminal spike either all staminate or with a few perigynia at the base (androgynous), lateral spikes either all pistillate or androgynous, perigynia hairy with a toothless or obscurely toothed beak, achenes 3-sided to round in cross-section. Species in this section are similar to those in the Acrocystis section, which have fibrous and leafy basal sheaths, and more distinctly toothed perigynia.

Carex richardsonii is not likely to be confused with other sedges, with a unique combination of: hairy perigynia 3mm long or less, scale-like bracts on pistillate spikes with a long sheath that is usually dark reddish, pistillate scales rather longer than the perigynia, and terminal spike all staminate. The long, dark sheaths can be eye-catching, though they are sometimes not so strongly red tinged.

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More photos

Photos courtesy Peter M. Dziuk taken in Houston, Pope and Washington counties.

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