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. Broom Sedge is a perennial tufted sedge commonly forming tussocks (or hummocks) in wet areas. The flowering stems (culms) grow 8 to 40 inches high, erect, slender, with a rough surface on the angles. Both flowering and non-flowering (vegetative) stems are produced. Stems are brown at the base. Late season growth of the plants may look very different from Spring growth.
The leaf sheaths are green with a U shaped summit. Basal sheaths are a little fibrous. Ligules are 2.3 to 4.8 mm long.
The leaf blades are only 1.4 to 3 mm wide, very narrow and slender, from 10 to 32 cm long ( 4 to 12 inches). There are 3 to 5 per flowering stem, vegetative stems have only a few leaves clustered near the top. Blades are V shaped when young.
The inflorescence is in racemose form and consists of 3 to 10 distinct spikes, usually all gynecandrous, that is with the staminate and pistillate florets on the same spike with the pistillate above. These spikes are dense to somewhat open as the lower spikes may have internodes of 2 to 12 mm. The entire inflorescence is arched to nodding, from 1.5 to 6 cm long, with the spikes clustered at the tip. Each spike is about 7 to 16 mm long and 3 to 9 mm wide, with an acute base and and acute to rounded tip giving an overall ellipsoid shape. The bract that forms at the base of the inflorescence is scale-like with a bristle tip.
The perigynia are ascending, pale green to golden-brown in color, lanceolate to elliptic in shape and 4.2 to 6.8 mm long and 1.2 to 2 mm wide. (about 2.8 to 4 times as long as wide) (The bladder-like sacs that enclose the female flower and later the fruit are called perigynia, singular - perigynium). The perigynium itself is 5-veined on each side, flattened on the margin with a thin wing and tapers to a pointed beak that is pale to golden brown at the tip and either with cilia or fine serrate edges. The scales of the female spikes are golden-brown or paler (similar to the perigynia), darker when mature, with usually more translucent margins, shorter and narrower than the perigynia and also tapering to a pointed tip. There are two stigmas per flower, 3 stamens. The perigynia become much narrower near the top of spikes.
Seed: Mature fruit is a brown elliptic shaped achene 1.3 to 1.7 mm long and 0.7 to 0.9 mm wide, much shorter than the perigynia, with a short point at the tip from the remains of the style. Carex achenes usually require 60 days of cold stratification for germination - or sown outside in the Fall.
Habitat: Broom Sedge grows from a short rhizomatous root system forming dense tussocks, not colonies, in wet meadows, swales, ditches and wet prairies. The species must have full sun and wet to mesic moisture conditions.
Names: The genus name, Carex, is from the Latin, being the old name for Sedges. The species, scoparia, means 'broom-like' coming from the Latin scopa meaning 'broom'. This is thought to refer to the shape of the spikes but the resemblance leaves a little to the imagination. The author names for the plant classification are: ‘Schkuhr’ refers to Christian Schkuhr (1741-1811) German artist and botanist who studied the flora of Wittenberg. One of his principal works was a monograph on sedges, with colored figures and containing a number of new species - title: Histoire des Carex ou laiches, contenant la description et les figures coloriées de toutes les espèces connues et d'un grand nombre d'espèces nouvelles from 1802. His work was recognized but added to in 1805 by ‘Willd.’ which refers to Carl Ludwig Willdenow (1765-1812), German botanist, a founder of the study of the geographic distribution of plants. He was director and curator of the Botanic Garden of Berlin.
Comparisons: Broom Sedge is classified in the sedge section Ovales wherein the species form dense clumps from short-rhizomatous root systems, have gynecandrous terminal spikes and gynecandrous or pistillate lateral spikes on racemose inflorescences; have lower bracts scale or bristle-like. Perigynia are erect to spreading, usually smooth surfaces, tapering to or rounded to a beak with two short teeth and an abaxial suture. Achenes are smaller than the perigynia bodies, biconvex, with a small pointed tip from the residual style.
Broom Sedge has two varieties, var. scoparia described above and var. tessellata which has the pistillate scales and the perigynium tip is reddish brown, chestnut or blackish contrasting with the lighter golden brown body of the perigynium. Also, the perigynium is only 2 to 2.6 times as long as wide. This variety does not exist in Minnesota. The other look-a-like sedge in Minnesota, in many of the same counties, is C. crawfordii (Crawford's Sedge) which is in the same form except that the inflorescence is always dense, never open, since the lower internodes are only 2 to 3 mm apart. Also, the perigynia are narrower.
Above: The lower spikes of the inflorescence usually have some separation on the raceme. Drawing ©Kenneth Kent Mackenzie (1940) North American Cariceae
Below: 1st photo - Sheaths have a U shaped summit. 2nd photo - leaf blades have a V shape.
Below: 1st photo - maturing inflorescence. 2nd photo - Mature perigynia showing the thin marginal wing, beak with two small teeth, body much larger than the enclosed achene (photo ©Linda W. Lewis, Wisconsin Flora).
Broom Sedge is one of over 150 sedges native to Minnesota. Var. scoparia is the only one of the two varieties found in Minnesota. It is found in counties on in the eastern 2/3rds of the state but rare south of the metro area. In North America it is found in all the states of the U.S. except Nevada, Wyoming, Texas and Florida. In Canada it is in all the lower provinces except Saskatchewan and Newfoundland.
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.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"