Big Bluestem is a perennial grass that likes dry open areas. It will reach full height only in full sun. It is a warm season grass, usually growing from short, scaly rhizomes and forming a dense tuft, above and below the soil level, and it forms sod. Rhizomes are not always present however.
Stems have a bluish to purplish-bronze color cast, often with a waxy bloom. The purplish-bronze color is more prominent in late season. It is very leafy at the base with some stem leaves.
Leaf blades vary from 2 to 20 inches long and up to 4/10ths inch wide. They frequently have a "v" shape with a prominent mid-vein, light green in color, with a reddish tinge near the tip.
The leaf sheath and collar area may be without hair but usually has fine whitish hair, particularly on the margins and at the base of the blade. The sheath is split and often has a purplish color at the base - this is most noticeable in late summer. The ligule is short with fine hair.
Inflorescence: The plant forms a conspicuous terminal seedhead in mid-August that breaks into 2 to 6+ branches, called 'rames' and up to 5 inches long; these bear repeating pairs of stalked and sessile spikelets. As the rames spread apart, particularly when they are three in number, they resemble turkey feet. The internodes of the rames are sparse to dense with whitish hairs.
Spikelets: On the rames are pairs of spikelets, one stalked which, when well developed which is the usual case, is staminate only, but sometimes it is absent or vestigial only and therefore sterile; the other spikelet is sessile, 3.5 to 12 mm long, and bisexual with three anthers, with glumes of about equal size. Awns form, 8 to 25 mm long with a twisted base and one bend. (Awns are bristle-like appendages at the tip of the seed that can make a twisting response to temperature and humidly changes and thus help the seed to work into the soil). Big Bluestem has about 10,000 seeds per ounce of weight. Disarticulation from the rame is below the sessile spikelet.
Habitat: Big Bluestem grows in prairies, meadows and areas with drier soil, but prefers slightly moist sites, and needs full sun, without which, it will lodge. It is top choice for erosion control when the site is moderately to well drained. It is a top forage plant and is used by birds for cover and nesting. It will not grow well where there is competition from weeds and cool season grasses. Cultivars are available from the nursery trade but this plant should be used for prairie restoration not necessarily the home landscape.
Names: The genus Andropogon applies to certain grasses that have hair on the spikelets resembling a man's beard. The word is derived from the Greek andros, meaning 'man' and pogon, meaning 'a beard. The species name, gerardii, is an honorary for French botanist and physician Louis Gerard (1733-1819) who developed a system of natural classification, published in 1761 as Flora Gallo-Provincialis. The author name for the plant classification, ‘Vitman’ refers to Fulgenzio Vitman (1728-1806), Italian botanist and clergyman. He developed the Brera Botanical Garden in Milan, which was restored in 1998.
Ornamental use: Several cultivars have been developed by the nursery trade that have a deeper bronze color to the stem and seed head. One is 'Blue Warrior' and another, even better, is 'Dancing Wind' (photo below). Note our article on Growing Landscape Grasses in Minnesota.
Above: 1st photo - Note the height of the plant when in full sun. Photo: ©Phoebe Waugh 2nd photo - The characteristic "turkey foot" panicle of the seed spikelets.
Below: Detail of the rames and spikelets at flowering time. Staminate spikelets have stalks. Note the awns with one bend. Rames generally have a purplish cast at flower maturity, sometimes yellowish.
Below: The ligule and collar at the leaf sheath showing the marginal hair
Below: 1st photo - A stand of Big Bluestem in the Upland Garden in 2002. 2nd photo - Mature grains - note the twisted awns.
Below: 1st photo - Detail of the spikelets at flowering time. Staminate spikelets have stalks. 2nd photo - The stems take on a purplish-bronze coloration in the fall. 3rd photo Gardener Cary George with a Big Bluestem in the Upland Garden. Late summer 1999
Below: A combination of Big Bluestem and Indiangrass (Sorghastrum nutans) surrounding a path in Upland Garden in 2014. The leafiness at the stem base can be seen.
Below: 1st photo - Drawing by Agnes Chase from Norman C. Fassett's Grasses of Wisconsin. 2nd photo- the cultivar 'Dancing Wind'.
Notes: Big Bluestem is indigenous to the Garden area. The plant was introduced to the Garden on Sept. 17, 1915 when Eloise Butler brought in a large clump from Glenwood Park (which partially surrounds the Garden and is now named Theodore Wirth Park). In her day the plant was classified as Andropogon furcatus. It has probably been present ever since and now is well established in the upland portion of the Garden.
Big Bluestem is native to Minnesota and all states and Canadian Provinces from the Rocky Mountains eastward. It is found in all of Minnesota except Cook County and a few other scattered counties. Andropogon is a wide-spread genus in tropical and temperate zones. Thirteen species are known in North America but only A. gerardii is native to Minnesota. One other species is found, Andropogon hallii Hack., /the sand bluestem or beardgrass; but that was introduced for roadside and wildlife planting, othewise it is more restricted to the Rocky Mountain States.
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"