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Minnesota Sedges

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Common Name
Gray's Sedge (Common Burr Sedge)

 

Scientific Name
Carex grayi J. Carey

 

Plant Family
Sedge (Cyperaceae)

Garden Location
Not in the Garden

 

Prime Season
Late Spring Flowering

 

Sedge Terms

 

Sedges differ from grasses by having a 3-angled stem and structurally different flowers where the female flowers are enclosed in a sac like structure called the perigynium, which is subtended by a single scale. Gray's Sedge is a native perennial loosely tufted sedge preferring a mesic to moist woodland environment. The flowering stems (culms) are smooth and grow 15 to 35 inches high, singly or a few stems in a clump.

Leaf Sheaths: Basal leaf sheaths are persistent, purplish-red in color. Upper sheaths are green. Ligules are rounded, 2.5 to 6 mm long.

The leaf blades are 4 to 11 mm wide and of medium length - 12 to 34 cm long (5 to 10 inches), 'V' shaped. There are 6 to 12 per stem. In southern locations the leaves can be semi-evergreen.

The inflorescence at the top of the stem has multiple spikes, 2.5 to 17 cm (1 to 7 inches)in total length. There are 2 (occasionally 3) lateral spikes on the lower section of the inflorescence that are pistillate. These are stalked with the lower 2 spikes separated by a short gap. The pistillate spikes are ascending, globular in shape and densely crowded and densely flowered with 8 to 35 flowers. Each pistillate spike can be 2.5 to 4.2 cm long, and thick - 2.6 to 4.1 cm wide. Styles have 3 stigmas. The terminal spike is a single short-stalked staminate spike. The staminate spike is very thin, only 1 to 4 mm wide and is 0.5 to 6.5 cm long. Once flowering occurs, it turns brown and withers quickly. Each pistillate spike has perigynia that are ovoid in shape, densely packed on the spike and radiating in all directions. (The bladder-like sacs that enclose the female flower and later the fruit are called perigynia, singular - perigynium). The bracts that form at the base of the lower spikes are leaf-like and long - 8 to 26 cm long. These usually do not have sheaths. The appearance of the female spikes is said to resemble a spiky club - or an ancient mace.

Each perigynium is strongly 16 - 25 veined, smooth but dull surfaced with the body gradually tapering to a poorly defined beak of 1.5 to 3 mm. The body of the perigynium is roughly 12.5 to 20 mm long and 4 to 8 mm wide. The appearance is swollen and bladder like. The scales of the pistillate perigynia are about half the length of the perigynium, 1 to 5 green veined, lanceolate to ovate-circular in shape, with a pointed apex and usually with a rough awn of up to 7 mm. There are three stigmas per pistillate floret.

Seed: Mature fruit is a brown ellipsoid achene, (basically 3-angled) with convex faces and a withering style. The angles of the achene are not thickened or knobbed. Each is about 3.3 to 4.8 mm long by 2.6 to 3.7 mm wide. Florets are wind pollinated. Fruits remain on the plant overwinter.

 

Habitat: Gray's Sedge grows from a base of short rhizomes, in mesic to wet conditions in deciduous forests, bottomland forests and alluvial soils. Plants prefer partial shade but will tolerate shade and full sun. It usually does not form colonies. The spiked club-like inflorescence is said to do well in both fresh and dried flower arrangements.

Names: The genus name, Carex, is from the Latin, being the old name for Sedges. The species, grayi, is an honorary for Asa Gray (1810-1888), American botanist, Professor of Natural History at Harvard and instrumental in unifying plant knowledge of North America and author of Gray’s Manual - Manual of the Botany of the Northern United States, from New England to Wisconsin and South to Ohio and Pennsylvania Inclusive. The author name for the plant classification - ‘J Carey’ is for John Carey (1797-1880), English botanist who travelled to the United States in 1830 with his 3 motherless sons and his brother Samuel. He then worked with Asa Gray in North Carolina in 1841 and returned to England in 1852. He contributed sections on Carex and Salix to Asa Gray's 1848 Manual (noted above). Gray considered him a near and faithful friend. Several species have been named for him.

Comparisons: Gray's Sedge is a member of the sedge Section Lupulinae, and has the distinguishing characteristics of usually not forming colonies, stems purplish to reddish at the base, basal sheaths not fibrous, wide V to M shaped leaf blades, raceme type inflorescences with multiple spikes, upper spikes staminate and lower spikes pistillate, lower bracts leaflike, 3 stigmas per floret. The sedges in this section have the largest perigynia of any Carex.

The most similar sedge like Gray's Sedge is C. intumescens, the Greater Bladder Sedge (drawing shown below), where the main difference is the perigynia only number 1 to 12 per spike and they are mostly ascending to spreading. This sedge is found extensively in Minnesota. The other sedge in our area that is somewhat confusing is C. lupulina, the Common Hop Sedge which is found in similar habitats to Gray's Sedge. The noticeable differences are the beak of the perigynia is longer and the perigynia do not radiate out in all directions, rather they are ascending. This makes the spike appear more cylindric and spiky instead of globular. The distribution however, is more broad - found in most counties on the eastern side of the state.

See bottom of page for notes on the Garden's planting history, distribution in Minnesota and North America, lore and other references.

upper plant parts Drawing

Above: The inflorescence - not the perigynia radiating out in all directions. Drawing from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.

Below: 1st photo - the stem base with purplish-red sheaths. 2nd photo - leaf sheath front view. 3rd photo - detail of a perigynium, drawing by Harry C. Creutzburg ©Kenneth Kent Mackenzie (1940) North American Cariceae

Stem base sheath perigynium

Below: 1st photo - note the withered remains of the staminate spike behind the pistilate spike. 2nd photo - detail of the inflated perigynia showing the clear vein structure.

spike perigynia details

Below: 1st photo - The staminate spike in flower. It is solitary at the top of the stem. 2nd photo - pistillate spikes in flower - they are below the staminate spike.

staminate spike in flower pistillate spike in flower

Below: Leaf detail showing the strong keel forming the "V" shape.

leaf leaf

Below: The rhizomatous root system with the purplish basal sheaths.

root system

Below: A comparison of the spikes, perigynium and achenes of some of the sedges from Sect. Lupulinae that are referenced in the "comparison notes" above. Drawing courtesy and ©Flora of North America

section Lupulinae details

Notes:

Gray's Sedge is not present in the Wildflower Garden. The species is found in the eastern half of North America with Minnesota and Ontario being at the northwest part of the range, then south along the Mississippi River States as the western edge of the range. Within Minnesota it is rare, with known populations in only 8 counties, most concentrated on the south-eastern side of the state. It is currently listed on the DNR's "Special Concern" plant list. It is is one of over 150 sedges native to Minnesota.

References and site links

References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.

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