Andropogon gerardi Vitman

Big Bluestem

Andropogon gerardii plant

Family - Poaceae

Habit - Perennial grass.

Stems - Erect, to 3 m, usually unbranched, circular in cross-section, glabrous, usually glaucous.

Andropogon gerardii NodeNode.

Leaves - Sheaths rounded on the back, glabrous or hairy, the uppermost sheaths not inflated, the ligule a short, stiff membrane with a hairy (fringed) margin. Leaf blades 8-50 cm long, 5-10 mm wide, glabrous or the lowermost ones hairy, especially near the base, relatively flat, the midvein noticeably thickened

Andropogon gerardii leaf baseLeaf sheath.

Andropogon gerardii leaf base

Andropogon gerardii liguleLigule.

Inflorescences - Palmate clusters of 2-4 spikelike racemes not enclosed by the subtending leaf sheaths, the racemes mostly 4-11 cm long, relatively stiff and straight, with a purplish brown coloration, the hairs on the joints of the axis and the spikelet stalks 1-4 mm long, white or yellow.

Flowers - Stalked spikelets staminate, similar in size and appearance to the sessile, perfect spikelets (but awnless), the stalk about 1?2 as long as the sessile spikelet (excluding the awn). Glumes 6-11 mm long, narrowly ovate, usually somewhat roughened and often also glaucous. Lemmas with the body 5-9 mm long, the awn 8-19 mm long, spirally twisted and bent near the base. Anthers 2.5-4.0 mm long.

Andropogon gerardii flowersPurple styles, yellow anthers.

Flowering - June - September.

Habitat - Prairies, glades, open rocky woods, railroads.

Origin - Native to U.S.

Other info. - This large species can be found throughout most of Missouri except for the extreme southeastern lowlands. This is a common grass in the habitats mentioned above. The blue glaucous coating on the stems and bluish color of the leaves give the plant its common name - "Big Bluestem."

The specific epithet has long been spelled "gerardii." The apparently correct orthography is that indicated at the top of the page.

Photographs taken in the Ozark Scenic Riverways, Shannon County, MO., 8-29-03, and at the Sunklands Conservation Area, Shannon County, MO., 7-26-04.


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