broomsedge bluestem
Andropogon virginicus L.

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plantinflorescence

Although broomsedge is a close relative of big bluestem (Andropogon gerardii), it is not a Midwestern prairie grass and is not common in Iowa. In fact, its occurrence in Iowa is documented by one specimen from Wapello county, collected in 1941 by Dr. Ada Hayden, the former curator of ISU’s herbarium and the first woman to earn a doctorate from Iowa State. Dr. Tom Rosberg (Drake University) also reports occurrences of this species in Appanoose and Ringgold Counties. Broomsedge is a common weedy plant in the eastern and southern U.S., where it occurs in abandoned fields, hillsides and thin woods. It is frequently found in disturbed areas, and is considered an indicator of poor soil. Broomsedge is poor forage for livestock, and is thought to inhibit more desirable forage species and Rhizobium bacteria, which form nitrogen-fixing nodules on the roots of many legumes (Bidwell, Redmon and Stritzke, 1995). Many landmanagers consider broomsedge highly undesirable. However, some people find broomsedge attractive or believe that it provides wildlife habitat, and its seed is sold commercially. The seed can be legally purchased because the USDA only lists broomsedge as a noxious weed in Hawaii, but it is strongly advised that broomsedge not be planted in Iowa. Broomsedge is native from northern South America to the southeastern U.S., with its native range barely extending into southern and southeastern Iowa, where it may be more common than herbarium records indicate. It has become established outside of its native range in California, Hawaii, Japan and Australia. The linear branches (rames) of the flowering heads of this species are quite hairy but are enclosed by conspicuous sheaths.

dark green: herbarium specimens

light green: reported

Etymology: Andropogon from the Greek andros = man and pogon = beard, as the hairy spikelets characteristic of this genus are said to resemble a man’s beard. The great Swedish botanist, Carolus Linnaeus (1707-1778) named this species and assigned it the specific epithet virginicus Latin = from Virginia, referring to the Virginia territory where the specimen viewed by Linnaeus had been collected.

 

Plants perennial, tufted, not rhizomatous. Culms 65-110 cm tall, the internodes solid and shallowly grooved or flattened on one side. Leaves with the sheaths open, strongly keeled, glabrous to scabrous; ligules 1-1.5 mm long, a fringed membrane; blades 11-31 (-52) cm long, 1.5-6 mm wide, with a prominent midrib, glabrous to hairy, at least near the collar. Flowering heads consisting of groups of 2-5 (7) linear branches (rames) subtended by sheaths 2.5-4 cm long and 2-4 mm wide; rames 1-2 (-3) cm long, 0.5-1 cm wide, mostly enclosed by the sheaths; internodes ca. 2 mm long, slender, long-hairy. Sessile spikelets 3.3-3.5 mm long, lower glumes with the keels usually glabrous below the midpoint and scabrous above, callus hairs 1-2 mm long; awns 6.5-18 mm long, straight. Pedicellate spikelets absent or rudimentary and less than 0.5 mm long; pedicels 4.5-5 mm long, long-hairy. Chromosome number 2n = 20.

 

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